The Bovine Testes-II: Role of Hormones During Pre and Post Natal Development

Abstract

Hormonal Regulation of Male Reproductive Function The Hypothalamus: The hypothalamus lies at the base of the brain and constitutes a part of nervous system. Anteriorly it is bordered by the optic chiasma and posteriorly by the mammillary bodies. The thalamus lies to its dorsal and sphenoid bone to the ventral borders. Many of its nuclei lie close to the third ventricle (Reeves, 1980). As in the adult life, the hypothalamus is involved in coordinating the function of fetal endocrine organs. The exposure to certain hormone stimuli, of fetal hypothalamus can bring about permanent changes contrary to the adult hypothalamus (Liggins, 1982). The vascular connection between the hypothalamus and anterior pituitary is established through superior and inferior hypophyseal arteries which serve to transport hypothalamic releasing and inhibiting factors to anterior pituitary. Venous blood carried from pituitary to hypothalamus also carries some hormones from pituitary to hypothalamus thus regulating their pituitary production by a short loop feed back system. Hypothalamus is the center to integrate inputs from CNS, the pituitary and the gonads. The median eminence, arcuate nucleus, suprachiasmatic nucleus and preoptic nucleus seem to contain the highest concentrations of GnRH (Palkovits et al., 1974). Norepinephrine stimulates and dopamine inhibits the GnRH release (Sawyer, 1975). Testosterone and estradiol receptors are present in hypothalamus and may be a potential site of steroid modulation of GnRH secretion (Greeley et al., 1975). GnRH is carried to the pituitary gonadotrophs through portal vesseis where it binds to goaadtroplig (Steinberger et al., 1978). GnRH causes the release of both LH and FSH which mediate both testicular androgen biosynthesis and spermatogenesis (Swerdloff and Heber, 1981).

Retained placenta in dairy cows living in an all-day cowshed rearing system

“…This is presumably due to the influence of fetal androgenic hormones from the testes of male fetuses, which can affect the incidence of retained placenta (Rezende et al, 2020). Androgen hormones produced by the testes negatively affect the hypothalamic-pituitary axis in the release of Follicle stimulating hormone (FSH) and Luetinizing hormone (LH) (Lodhi and Qureshi, 2000). The inhibition of FSH and LH production will have an impact on decreasing estrogen production (Mark and Michael, 2013).…”