Lec 2 Flashcards
What role does testosterone play in the development of sexual organs?
Testosterone in the embryonic testis stimulates the development of male sexual organs. If testosterone is not present, female sexual organs will develop.
What gene is responsible for stimulating the development of male reproductive systems after conception?
The SRY gene is responsible for stimulating a cascade of testis development.
From which ducts do the internal reproductive structures develop?
The internal reproductive structures stem from ducts that will develop into either male (Wolffian) or female (Müllerian) structures.
What is puberty and what changes occur during this period?
Puberty is the age at which the female or male gonads become capable of releasing gametes (oocytes or spermatozoa) and manifesting complete sexual behavior. In females, the onset of cyclic periods occurs, genital organs increase in size, and secondary sex characteristics appear. Puberty is a link between immaturity and maturity.
What physiological changes indicate sexual maturity?
Sexual maturity is often marked by the appearance of secondary sex characteristics, such as the estrus cycle in females and ejaculation in males.
What happens to primordial germ cells and follicles in the ovaries before puberty?
Primordial germ cells migrate from the yolk sac to the developing ovaries, where they are surrounded by a single layer of follicular cells and begin meiosis. Follicles that develop in the ovaries before puberty develop only to the stage of having a theca interna and then undergo atresia until puberty.
What roles do progesterone and oestradiol play in the onset of puberty and LH surge?
The central nervous system requires priming with progesterone for the first ‘silent’ estrus to occur. Secretion of oestradiol activates the LH surge, which is crucial for ovulation and corpus luteum formation.
How does nutrition affect the onset of puberty and reproductive hormone synthesis?
Nutrition, particularly energy and protein, is essential for optimizing reproduction. Malnourished individuals may lack ovarian activity due to the suppression of luteinizing hormone. Dietary restriction results in a gradual reduction of the growth rate of the dominant follicle and affects the synthesis and release of GnRH, FSH, LH, and GH.
How does the season of birth and year influence the onset of puberty in animals?
In seasonal breeders, such as the ewe, mare, and queen cat, the age at which puberty occurs is influenced by the effect of the season of the year. Heifers born in autumn attain puberty earlier compared to spring-born heifers.
How do melatonin and climate affect the age at which animals reach puberty?
Melatonin, secreted by the pineal gland, influences hormonal secretion and its activity is dependent on the photoperiod. Animals living in the tropics reach puberty at an earlier age than those in temperate climate regions.
What is the ‘ram effect’ and how does exposure to males influence the timing of puberty onset?
The ‘ram effect’ is the phenomenon where placing a ram with ewes before the breeding season increases the frequency of pulsatile LH release, stimulating the onset of cyclical activity. Exposure to the male of the species advances the timing of the onset of puberty.
Define the Interaction?
Among season and other Environmental factors affecting breed,Nutrition, milk production,suckling and reproduction was proposed.
