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REPRODUCTION IN THE FEMALE ANATOMY AND HORMONES

REPRODUCTION IN THE FEMALE ANATOMY AND HORMONES. Bambang ariyadi. The Ovary. Hens only have a single functional ovary and oviduct (the left one). Ovulation

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REPRODUCTION IN THE FEMALE ANATOMY AND HORMONES

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  1. REPRODUCTION IN THE FEMALEANATOMY AND HORMONES Bambang ariyadi

  2. The Ovary • Hens only have a single functional ovary and oviduct (the left one).

  3. Ovulation • This is the act of a mature follicle(yolk) being released from the ovary.It will travel down the oviduct havingalbumen, shell membranes and shell applied around it. • Oviposition • This is the act of laying an egg. Theegg is released from the shell glandinto the world. Ovipositionnormalproceeds with the large end of the egg appearing first.

  4. Luteinizing hormone (LH) • A glycoprotein hormone released from the adenohypophysis. It is very important in stimulating sex-steroid production from the ovary. • Follicle Stimulating Hormone (FSH) • A glycoprotein hormone released from the adenohypophysis. It stimulates small follicle development. The number of follicles a hen has isdetermined before she hatches as achick. Hens have many thousandfollicles and only a few of themactually go so far as to become eggs

  5. Control of Pattern of Ovulation • Chickens lay eggs in sequences or clutches. • Normally, this egg laying pattern follows certain rules. • The first rule is that the first egg of asequence is laid within 1-2 hours after the house lights come on. • Secondly, each egg in a sequence is laid later in the day. • Thirdly, the last egg of a sequence is typically laid about 9-10 hoursafter the lights come on.

  6. Sequence and Ad libitum Sequence A sequence is a period of severaldays of continuous laying of one egg per day. Prime Sequence The longest sequence a hen lays. Itis typically seen about the time of peak egg production. Ad libitum A term meaning to eat to full consumption. Ad libitum-fed burds have feed available to them continuously.

  7. How do double-yolked eggs happen? When two ovarian follicles aredeveloping at a similar rate, both willovulate at the same time (identicalfunctional maturity) resulting in adouble-yolkedegg. This condition isnormally seen at a rate or 2-3%during the first 6 weeks of the layingperiod. As flocks are over-fed, the incidence increases. Some hatching egg producers monitor the incidenceof double-yolked eggs to determineif they are under-feeding or overfeeding the flock.

  8. How do blood spots in eggs happen? Blood spots are normally a result of aproblem that occurs at the time of ovulation. A normal follicle ruptures at the stigma which is a stripe on thefollicle wall that is quite devoid of blood vessels. Sometimes ovulation can occur outside the stigma,involving rupturing a small bloodvessel which can leak blood to asmall or to a large extent.

  9. ENDOCRINE SYSTEM • The endocrine system is the collection of glands that produce hormones that regulate metabolism, growth and development, tissue function, sexual function, reproduction, etc. • The endocrine system is composed of a number of glands that produce, store, and secrete hormones . • Hormones can be classified into two broad categories, according to structural properties: • (1) protein hormones • (2) steroid hormones

  10. Majorendocrine glands in poultry

  11. The Hypothalamus • The hypothalamus is the reproductive controller of the hen. • It receives input from other brain centers throughtiny neuro-transmitters, as well as signals directly from the environment. • The reproductive system is driven by hormones. • Hormones are verysmall chemicals that are produced and released in one organ, but aretransported by the blood stream to make something happen in another organ.

  12. The Hypothalamus • The purpose of the hypothalamus in the control of reproduction is torelease very small protein hormones (gonadotrophin releasing hormonesalso known as GnRH) that stimulate the release of “gonadotrophin”hormones from the neighboring adenohypophysis (also called the anterior pituitary). • There are two types of GnRH in chickens. • There are special cells in the hypothalamus that are thought to receive light energyat photostimulation in response to the days becoming longer.

  13. The Hypothalamus • The light response involves the stimulation of specialized cells within the brain. • That means that light intensity must be adequate tohave the light energy penetrate the feathers, the skin, the skull and the brain. • There is a network of blood vessels that link the hypothalamus and the adenohypophysis. • This means that the message from the hypothalamus(GnRH) is sent directly to the adenohypophysis in a rapid manner.

  14. The Adenohypophysis (anterior pituitary) • The adenohypophysis is the organ that produces the hormones thattravel to the gonads to actually stimulate reproductive function. • The adenohypophysis receives messages from the hypothalamusand, if the timing is right, it releases two important gonadotrophin hormones.

  15. The Adenohypophysis • One hormone is luteinizing hormone (LH) which is essential for sexualmaturation and for daily egg production to occur. • The role of LH is to stimulate the production of sexsteroids(steroidogenesis) in the follicles in the ovary. • It also stimulatesandrogen hormone production from the testes of males. • This hormone is an integral component of the day-to-day events of ovulation.

  16. The Adenohypophysis • The second hormone is follicle stimulating hormone (FSH). • As itsname suggests, this hormone is thought to be involved in thedevelopment of many tiny follicles days or weeks before they become competent to ovulate. • The role of FSH in promoting sex steroidproduction in the ovary is not thought to be significant, as smallamounts of LH can do as much as larger amounts of FSH.

  17. The Neuro-Hypophysis • The neurohypophysis lies adjacent to the adenohypophysis. • Theneurohypophysis(also know as the posterior pituitary) differs from theadenohypophysisin that it communicates with the higher brain by nerves. • The neurophypophysis produces argininnevasotocinand mesotocin. • Arginine vasotocin is presumed to be involved in the smooth muscle contraction needed at oviposition.

  18. Control of Pattern of Ovulation • Chickens lay eggs in sequences or clutches. • It is the release of GnRH from the hypothalamus that results in layingsequences. • About 6 hours before a hen ovulates she experiences a surgeof GnRH which results in a surge of LH. • If there is a mature pre-ovulatory follicle it will respond tothis burst of LH release and will produce progesterone. • This progesterone will stimulate further LH release and so on.

  19. Control of Pattern of Ovulation • This is a “positive feedback” where the release of one hormone triggers further release of another hormone. • Ovulation is the end point, about 6-8hours after this initial LH surge. • Normally ovulation follows oviposition by a period of about 15-45 minutes. • This is not the case when a hen lays an egg late in theafternoon, many hours after the first egg of a sequence was laid.

  20. Control of Pattern of Ovulation • In this case, the hen does not ovulate soon after oviposition because it is too late in the day. • She will not lay an egg the next day (pause day). • The hen will hold the mature F1 follicle, overnight, and ovulate it at the very start ofthe next open period for LH release she experiences. • This means she will lay early in the day and a new sequence will begin.

  21. Control of Pattern of Ovulation • The fact that the hens holds the follicle over night(approximately an extra 16 hours) means that the first yolks of asequence are heavier as she still applies egg yolk in that time period. • Since yolk size affects egg size, first of sequence eggs are heavier than aresubsequent eggs in a sequence. • To record sequence length for a population, individual laying records must be obtained.

  22. Kontrol hormonal fungsireproduksi • Pituitary anterior mensekresi gonadotropin (FSH) dan (LH) yang fungsiutamanyameregulasifungsi ovary. • Sekresi gonadotropin diregulasiolehGnRhdarihipotalamus. • Level puncakLH berlangsung 4-6 jam sebelummasaovulasiterkaitdenganpeningkatan level progesterone dalamdarahayamdanburungpuyuh.

  23. Kontrol hormonal fungsireproduksi • Prolactin disekresioleh pituitary anterior yang berperanpentinguntuksifatindukselamamasamengeramdanjugauntukmenekanfungsi ovary. • Pituitary posterior mensekresi arginine- vasotocin yang menyebabkanoviposisidanstimulasireabsorbsi air olehductus colectivusdalamginjal.

  24. Kontrol hormonal fungsireproduksi • Sex steroiddisintesisdarikolestrolmelalui metabolic pathway dari pregnolone, progesterone, androgen sampai estrogen dalam ovary. • Ada 3 tipeselsteroidogenic yang disebutselgranulosa, selteca interstitial dalamtecainternadansel aromatase dalamtecaeksterna. • Progesteronediproduksiolehselgranulosadansel interstitial, danselterakhirtsb mengubahprogesterone menjadiandrogen. • Sel aromatase meng-convert androgen menjadi estrogen.

  25. Kontrol hormonal fungsireproduksi • Folikel kecil merupakan tempat utama produksi estrogen, sedangkan folikel F1 memproduksi progesteron. • Responterhadap FSH lebihtinggidalamfolikelkecildaripadafolikel F1. • Sebaliknya respon terhadap LH lebihtinggipadafolikel F1 daripada folikel kecil.

  26. Kontrol hormonal fungsireproduksi • Ovarian sex steroid berperandalamregulasipertumbuhan oviduct,ovarian steroidogenesis, integritasfolikeldankarakteristik organ reproduksi sekunder. • Sekresi albumin di dalam magnum dankomponenkalsium di dalamshell gland (uterus) yang di stimulasioleh(berurutan) progesterone dan estrogen.

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