sorry guyz.. my col started.. loads to do... off till december...

mnemonimania: the vaccines courtesy my zoology sir and myself.

the vaccines used nowadays are of many types..

attenuated vaccines : weakened pathogens unable to cause disease but sufficient to activate our immune response..

eg. Influenza, BCG, OPV, yellow fever, small pox..

remembered as hI BOYS or boy's eye(I)

killed : dead pathogens used but their antibody sites are still funtional

eg. TAB vaccine, Typhoid vaccine, salk vaccine for polio, rabies, plague, typhus fever vaccine, and cholera

remembered as: TaTa SiR,Please Take Care.

cell fragments: this is real hell to remember even if u use a mnemonic.

eg. PCM : polysaccharide of cell wall of meningococcal bacteria

PCP: polysaccharide of capsule of pneumococcal bacteria

HBP : hepatitis B polypeptide.

mnemonimania again... on animal husbandry

milch breeds of cow : Gir, sahiwal, red sindhi, deoni

d mnemonic : sahi ghar red deo...

drought breeds: malvi, nageri, halliker, kangayam

d mnemonic: malvi nagar hall kaha gaya???

general utility breeds: haryana, kankrej, tharparkar, ongele

d mnemonic: haryana k tharparkar ki ungli.

buffaloes now..

nili ravi k pass jaffrabad, surat aur nagpur me bada war hua...

the breeds: nili ravi , jafrabadi, surti, nagpuri, mehsana, bhadawari.

the most important buffalo breed is murrah which i cudnt accomodate in my mnemonic.

goats now..

the breeds: malabari, bengal , jamunapuri, kashmiri pashmina, marwari, gaddi, berari, beetal

malabar, bengal, yamuna(jamuna) aur kashmir meri gaadi ferari me gaya.....

why leave horses...

the breeds: manipuri, bhutia, kathiawari, zanskari, spiti

the mnemonic: manipur ka bhutia ghatia sanskar se spit karta hai...

that's it... but i dont think the horses, goats and all are that important...

male reproductive system

Male reproductive system

Lets start from ovotestis to testis transition. (see earlier blog for information about mullerian and wolfian duct, and ovotestis)

The Y chromosome has testis determining factor (tdf gene)

Y à(transcription)à RNAà(translation)àprotein

Now, this protein acts on adrenal cortex to secrete sexocorticoid called androgen.

Androgen does two things:

1. degenerates cortex part of ovotestis

2. It promotes medulla part of ovotestis. Thus, it promotes differentiation of gonadal cells to form interstitial cells and sertoli cells. These two help in spermatogenesis, but don’t form sperms.

Note : sperm mother cells are extra-gonadal and extra-embryonic, i.e they are not original residents of gonads.

Sertoli cells secrete MIS (mullerian inhibiting substance). It acts on mullerian duct and blocks its growth.

Interstitial cells secrete testosterone and promotes wolffian duct with form epididymis, vas deferens and vasa efferentia i.e whole ductous system.

This process is completed in 2^nd month of foetus.

è Testes

It is formed in abdominal cavity (not in scrotal sac). It is also connected with dorsal body wall.

Before parturition, in 7^th month of foetus, testosterone level in blood increases, which widens inguinal canal (inguinal canal connects abdominal cavity to scrotal sac). This results in descending of testes from abdominal cavity to scrotal sac (extra abdominal position but abdominal origin).

All blood vessels, nerve firbes, lymph vessels connected with muscles called cremaster muscles from dorsal abdominal wall. This structure is called spermaticord. It connects testes to dorsal body wall, and also supplies blood to it.

The mesentery of testes is called mesorchium

Note:

Mesentary = structure which connects an organ to dorsal body wall in human eg. Mesovarium is mesentery of ovary.

Omentum: connects organ to stomach

Ligament: a structure which connects one organ to another organ except stomach.

*** In birds and frog, mesorchium is connection between testes and kidney.

Lower portion of testes is connected with scrotum by gubernaculum. Similary, two testes in scrotum are separated by septa scroti.

Temperature of scrotum is 2 – 2.5 degree Celsius less than body for proper functioning of testes.

As testes descends, Inguinal canal is completely plugged with Connective tissue.

*** But in rat, bat testes descends to scrotal sac only during breeding season,i.e Inguinal canal is permanently open. Or, temperature varies from non-breeding to breeding season.

Empty scrotal syndrome

Testes remain in abdomen, temperature is high. This is also called cryptorchidism (crypt: hidden). It leads to steriliy.

As a cure, during birth, a booster dose of testosterone or Luteinizing Hormone (Interstitial Cells stimulating Hormone) is given which helps in descend of testes.

*** In whale, elephant, seal, spiny ant eater, platypus etc., testes is permanently present in abdominal cavity. i.e Cryptorchid condition is normal in these organisms. Inguinal canal is non functional in thes organism. In platypus, temperature of environment is so low that testes shud remain in abdomen.

Sometimes, two testes are fused together in scrotal sac, if septa is not developed. This is called synorchdism or testes fusion syndrome. It may(but not always) lead to sterility.

As body temperature rises, the scrotal sac has dartose muscles. It is highly thermosensitive. It enlarges so that surface area of srotum increases and heat radiates out faster. If temperature is low, it constricts and testis gets near the crater of inguinal cavity and takes body heat from abdominal cavity. Cremaster muscle is also heat sensitive.

Inguinal hernia: If inguinal canal remains open, part of large intestine just enters and exerts pressure. So, it descends.

Testes has 3 coverings, tunica vaginalis (outer coelomic peritoneum), tunica albuginae ( white fibrous and actual covering), and tunica vasculosa ( vascular part, with blood supply)

Hydrocoel = when coelomic fluid amount in cavity of vaginalis increases.

Some of the tunical albuginae enters into inner region of testes and divides it into 250-300 testicular lobules.

Each testicular lobule has 1-3 semeniferous tubules (highly coiled) where spermatogenesis occurs.

All semeiferous tubules open into 20-30 straight tubuli recti. Tubuli recti opens into highly coiled rete testes. It is internally lined by cuboidal epithelium.

Rete testes opens into small 10-20 ducts called vasa efferentia.

Vasa efferentia is internally lined by ciliated cells and endocytic cells. Ciliated cells support the movement of sperm to epididymis(as it is not fully mobile yet). Endocytotic cells feeds on cell debris, external fluid etc.

Vasa efferentia opens into paired highly coiled duct (around 6m… no I didn’t measure it anyways…I’ve better jobs to do)

In epididymis, movement of sperm is by peristalytic movement and segmental movement.

Epididymis is lined by basal cells(undifferentiated cells, form new principle cells) and principle cells ( have non motile stereo cilia, secrete nutritive substance and also secrete substance for maturation of sperm)

The sperm becums active and motile when it stays in epididymis for at least 18 hours. Thus, epididymis is responsible formaturation and storing sperms. Unejaculated sperms degenerate and absorbed there.

Principle cells of epididymis secrete maturation factor called glycerophosphocholine(GPC). GPC is incorporated with sperm membrane and makes it more stable and less permeable(because acrosome has a lot of digestive enzymes, so, GPC is needed)

Epididymis has 3 parts, caput (head), corpus(body) and cauda(tail).

Vasa efferentia opens into capute. From cauda, another duct develops called vas deferens. It is also lined by stereo cilia. Main part of storage of sperms is vas deferens. It is 35 m long.

Vas deferens is associated with spermaticord and enters into abdominal cavity. Swollen part is called ampulla of vas deferens. Vas deferens passes between rectum and urinary bladder.

As duct of seminal vescicle opens into vas deferens, it is not called ejaculatory duct.

Both the ejaculatory duct open into a common duct called urethra.

Urethra has 3 parts: -

1. prostatic urethra(around 5 cm): prostate gland secretes prostatic secretions at semen here.
2. membranous urethra (smallest, just around 1-2 cm)
3. penile urethra (around 20 cm)

At junction of penile urethra and membranous urethra,, paired glands called cowpers glands peresnt which secrete mucous.

Penis

It has 2 types of muscles: -

1. Corpora cavernosa: present dorsally, column like and paired
2. corpus spongiosum: single column like and present ventrally

In corpus spongiosum, penile urethra is present.

These muscles have a large no/- of sinusoids. Sinus is very vascular(has rich supply of blood). This helps in erection of penis.

At action of acetyl choline, the whole system of muscles becums erect.

At terminal part of penis, corpus spongiosum becums enlarged and now called glans penis. It is covered with loose flap of skin called as prepuce/ foreskin.

*** during circumsition, the prepuce is cut.

Prepusal glands called glands of Tyson are present between glans penis and prepuse. It secretes oily/waxy substance and prevents from infection.

Epididymis is absent in frog, fish and toad. In these, maturation and storing of sperms happens in semeiferous tubules.

Tubuli recti + rete testes + vasa efferentia = intra testicular genital ductus system

Entire testes + epididymis = testicle.

Some Glands:-

Seminal vescicles

• paired
• present between urinary bladdr and rectum
• secrete seminal fluid (contributes 60% – 70% of total semen)

Seminal fluid contains

1. fructoseè nutrition to sperms
2. prostaglandins è it makes uterus more receptive to sperm movements by inducing anti peristalytic movements in uterine canal
3. seminogelin: it is an important clotting protein
4. clotting factor: important for coagulation of semen in female genetaria
5. inosytol } support clotting
6. citrate } -do-
7. ascorbic acid } -do-
8. fibrinogen } -do-
9. other proteins

Prostate gland

• single
• prostatic secretions contribute 20% - 30% of semen

Prostatic secretion contain

1. ionic calcium (due to this, semen looks milky in colour) } contribute to
2. Phosphate ion } alkalinity
3. carbonate ion } of semen
4. spermine(a nitrogenous base like adenine):reacts with phosphate to form crystalline spermine phosphate
5. amino acid }
6. profibrolysin } important for clotting
7. clotting proteins }

Prostate is essential for activation of sperm. Its removal leads to sterility

Cowper’s gland

• secretes mucous
• lubrication of urethra

Semen

• each ejaculation contains 3-4 mL of semen
• it contains 80 – 100 million sperms per mL
• if sperm count decreases to less than 20 million, it leads to steriliy
• pH around 7.3-7.4 (slightly alkaline)
• In entire body, only semen has fructose.

Diseases

Prostatis: inflammation of prostate gland due to infection

It leads to dysurea (painful urination)

Benign prosatic hypertrophy: -

• Enlargement of prostate gland
• Completely normal
• 1^st during puberty, 2^nd during age of around 40 years
• Cells become enlarged
• May lead to dysurea and nocturea

Prostatic cancer

• due to removal of prostate gland
• testosterone promotes Pr. Cancer. Hence, castration(removal of testes) may cure this if done in early stages of cancer.

Impotence

• Inability to erect the penis in adult male
• Due to behavioural, neural, physiological or psychological disturbance.

Human reproduction: - Basics of basics

Reproductive organs à 2 types

Primary( hence forth referred as 1* ) repro. Organs = which form gametes and secrete sex hormones. Eg. Gonads

Secondary(hence forth referred as 2*) repro. Organs = which assist 1* sex. Organs and help in transportation of gametes, support and development of embryo. Eg. Other sex. Organs.

In a 5-6 week old foetus, ovotestis is present, i.e till now, u cant say whether foetus is male or female. The ovotestis have a cortex(peripheral part which makes ovary) and medulla(central part which makes ductous system of male reproductive system) and 2 funnel like structures present.

The two funnels are mullerian duct (for making female repro.system) and wolffian duct (for making male repro. system)

some things about sexual reproduction in animals

Sexual reproduction

Individual develops by process of gametogenesis, fusion, zygote formation and then embryogenesis.

Due to geneflow, variation is uniformly distributed in the population after a long time.

It maintains vitality of population

Let me introduce you to some terms

Protandry : male reproductive organs of an amphisexual organism matures first eg. Amphioxus, herdmania, sponges

Protogyny : female reproductive organs of a bisexual organism matures first eg. Earthworm

Seasonal breeder: breeds in only one season of the year. Eg. Birds usually breed in winter (except the birds in captivity)

Ant. Continuous breeder eg. Humans.

Sexual life of an organism can be broadly categorized as juvenile phase (pre-reproductive phase), mature phase (reproductive phase), and senescent phase (post- reproductive phase)

Hormones are responsible for changing of phases. Sex hormones inhibit transition to senescent phase.

Reproductive phase can be divided into menstrual, pre-menstrual and post menstrual phases in primates, and in non primate mammals, into estrous, pre-estrous and post-estrous phases.

In non primates, breeding season influences by hormones. Hormones are controlled by nervous system and photoperiodism.

Eg. Light regulates the reproductive cycle in many organisms.

Like in birds, breeding season is November to January because daylength is less during this time. Likewise, it is seen that rats cant reproduce if constantly kept in light.

Events of reproduction

Sexual reproduction can be divided into 3 phases.

Pre fertilization events : It involves gametogeneseis and gamete transfer.

Special methods of gamete transfer

1. Gymnophiona ( icthyofish) : A member of Apoda, male has protrusible cloaca which enters into the female cloaca
2. Necturus ( also mud puppy and salamander) : male release spermatophore and female picks it up thro cloacal lip.

In external fertilization, water is the medium of gamete transfer (because gametes will die if fluid medium is absent).

Fertilisation events : male gamete fuses with female gamete

Fertilization is of two types

1. Endogamy = self fertilisatino
2. exogamy = cross fertilisaitno

Exogamy is again of two types

1. external fertilization
2. internal fertilization

For external fertilisaitno, large no/- of gametes have to be produced in right areas and in right time for proper development and replacement of individual as chance of predation is high and life span of gametes is low.

Both gametes are released in same time (temporally) and in same place (spatially).

Post fertilization events : It includes zygogenesis and embryogenesis

Zygote : full of hybrid genome. It is vital link between 2 sucessive generations

Embryogenesis

1. Oviparous (egg laying):eggs are either fertilized or unfertilised
2. vivypary (born young)
3. ovovivipary : fertilization and development in internal. The child is born young but it develops in egg inside female without taking nourishment from female

Gynogenesis

After fertilization, the whole sperm degenerates but egg is activated.

Sperm just activates the egg, but doesn’t contribute to genome.

Eg. Planaria, Durgesia

Parthenogenesis

Development of individual from unfertilized egg is called parthenogenesis.

It is of two types

1. Complete parthenogenesis: all individuals develop parthenogenetically. Hence, all individuals are females. Males are absent from in their species. Eg. Lacerta saxicola armeniaca (copasian lizard), Typhlina brahmina (smallest Indian snake)
2. Incomplete parthenogenesis : Individuals develop both parthenogenetically and zygotically. Eg. Bee { queen bee = 2n, worker bee = 2n, Drone = n} only drones (males)are produced parthenogeneticaly.

Note : worker bee and queen bee(females) both are diploid and born from zygote. The queens egg laying apparatus changes to sting apparatus in worker bee. That’s why u can meddle with queen but not with her maids!!!

Aphid and Daphnia show cyclomorphosis.

In wasp, one generation, all are haploid (produced parthenogenetically) and next generation, all are diploid. This is called cyclic parthenogenesis

In turkey, partial parthenogenesis is seen. 40% males are parthenogenetic. 60% males and 100% females are produced by fertilized egg.

Parthenogenesis can also be divided into 3 as:-

1. Arrhenotoky: only male develop parthenogenetically eg. Bees
2. Thelytoky: only females develop parthenogenetically eg. Lacerta saxicola armeniaca, Typhlina brahmina.
3. Amphitoky: both males and females develop by parthenogenesis eg. Aphids, Daphnia.

types of asexual reproduction

Types of asexual reproduction

1. Binary fission

One individual breaks into two. It is mitotic(in eukaryotes) or amitotic (in prokaryotes) process.

Eg. Amoeba.

Types of binary fission

Simple (irregular)

Fission can take place from any arbitrary plane of body

Eg. Amoeba.

Longitudinal fission

Fission takes place through the longitudinal plane

Eg. Euglena, trypanosome, giardia, lesihmania

Transverse fission

Fission takes place along the transverse plane

Eg. Paramecium (the part without cytostome i.e the upper part is caller proter and the part with cytostome i.e the lower part is called opisthe )

Eg2. planaria

Oblique fission

Mostly in dinoflagellates, ceratium

In organisms which undergo binary fission, there is no concept of senescene or natural death

It is mode of reproduction in favourable conditions.

Quesn : What will happen if paramecium is kept constantlyin favourable condition? (assume that only binary fission takes place and sexual reproduction doesn’t take place)

Ans. Paramecium population will die as the surface area volume ratio increases rapidly with each division. So, metabolic rate increases rapidly that results in their death.

That is why they involve in sex. Reproduction by conjugation.

2. Multiple fission

It takes place during unfavourable conditions. Usually, Cyst is formed and many nuclei are produced

Eg. In amoeba ,sometimes, nucleus divides repetitively but no cyst is formed. It is called psuedopodiospores.

If cyst also develops in the amoebulae thus formed, it is called encysted spore or encysted amoebulae.

Multiple fission is of two types.

Schizogony

In protozoans, a trophozoite increases in cell size and its nucleus divides repeatedly along with some organelles. The organism in such condition is called as schizont. The schizont eventually ruptures, releasing merozoites

Sporogony

Sporulation involving multiple fission of sporonts, resulting in formation of sporocysts or sporozoites. It can also be seen as reproduction by asexual division of spore or zygote.

3. Plasmotomy

(plasmo = cytoplasm , tomy = cut)

Only cytokinesis but not karyokinesis takes place. It is a modified multiple fission

As u may have guessed, it can be seen only in multinucleated organism.

Eg. Opalina ( it occurs in seminal vesicles of earthworm)

Eg2. pelomyxa (also called as giant amoebulae)

After plasmotomy, some cells may get uninucleated, but with time, karykinesis occurs (for development)

4. Regeneration

This can be seen only in organisms with low organization level.

Eg.. sponges, coelentereates upto echinoderms.

5. Budding

It is of two types

Internal budding

Eg. Gemmules formation (mesoglear) in sponges. It is protected by spicules

External budding

Eg. Hydra, sponges, tunicates etc.

In hydra budding takes place towards proximal end.