Endocrinology of reproduction Hormone:. Is the a physiologic , chemical substance synthesized and secreted by ductless endocrine gland, which passes in to the circulatory system for transport, hormones inhibit ,stimulate, or regulate the functional activity of the target organ or tissue. Hormones can be classified according to either biochemical structure or mode of action. Endocrinology of reproduction

The biochemical structure of hormone includes *glycoprotein *Polypeptides Steroids* *Fatty acids and amines

Structure of hormone:. According to their chemical structure, the H.S of Reproduction are divided in to 4 group:. -proteins :. These are polypeptide hormone e.g. oxytocin , FSH , LH. -Steroids:. There are derived from cholesterol e.g. testosterone -Fatty acids:. There are derived from arachidonic acid e.g. prostaglandins - amines:. These compounds are derived from tyrosine or tryptophan e.g. melatonin

Release of hormone The C.N.S play important role in reproduction by control of the secretion and release of hormones. There are higher centers in brain control on the reproduction activity and this centers under specific effects release specific factors which effects on specific glands (endocrine gland) which release specific hormones. These centers called neuro endocrine Glands which includes:. Hypothalamus- -Pineal gland

1. Hypothalamus:. The C.N.S effect of all function of the body by translation the environmental effect to internal effect and this means person communication cycle between the neural effect and convert in to hormonal effects. There for the hypothalamus and its secretions from releasing factors is the communication cycle between the neural effects and converted in to hormonal effects there fore it is the communication cycle between the external environmental and convert in to hormonal effects.

It is secretion this hormones which called Releasing Factors or Releasing hormones which produce from specific cells in the hypothalamus. The hypothalamus is a neuro endocrine gland that’s forms along the floor and lateral wall of the third ventricle of the brain it is closely linked with pituitary. The hypothalamus portal blood system connects the hypothalamus with the anterior pituitary gland and is the route by which hormone of the hypothalamus reach the anterior pituitary. The hypothalamus hormones are released form the terminal of axons in to blood vessels that serve the anterior pituitary.

The Releasing factors is Principal function Chemical class Hormone FSH and LH release peptide Gonadotropin-releasing (GNRH) 1- ACTH release Corticotrophin-releasing H. (CRH) 2- Prolactin release Prolactin -releasing H. (PRH) 3- Prolactin retention Prolactin –inhibiting H. (PIH) 4- Release of GH Somatotrophic releasing H. (SRH) 5- TSH release Thyrotrophic releasing H. (TRH) 6- This piptide hormone of 10 amino acids and can prepare and use it. Ti is given by injection only and not use by mouth.

2.Pineal gland The pineal gland is located posterior to the hypothalamus between the hemispheres of the brain. It is embryonic origin is the brain, but direct connection to the central nervous system is lost during development with innervations there after coming from sympathetic nerves, however the pineal gland responds to environmental light thing and senses changes in photoperiod (day length). The best characterized hormone of the pineal glands is melatonin a derivation of amino acid tryptophan. Darkness cause increased sympathetic activity to the pineal gland which increased the secretion rate of melatonin. The role of as a regulator of reproduction activity by either stimulating or inhibiting.

Gonadal function The long duration of high melatonin secretion during short photoperiod (long nights) Switches on short – day breeders such as sheep and goats and switches off long – day breeders such as horse. The effects of melatonin could be direction the hypothalamus or called be indirect by initiating release of other physiologically active compounds.

The endocrine glands 1- The anterior pituitary glands:. The glands subdivided in to three distinct anatomic . Parts: 1.anterior 2.intermediate 3. posterior lobes.

The cell type in the anterior part have traditionally been classified on their staining characteristics in to a granular and granular chromophils. The chromophils are divided in to acidophilus and basophiles. The anterior pituitary has five different cell types secretion six hormones ,by type cell , the somatotropes secrete growth H., corticotropes secrete adeno – corticotropic H. (ACTH), mamonotropes secrete prolactin, thyrotropes secrete thyroid stimulating H.(TSH), and gonad tropes which secrete follicle stimulating H.(FSH) and luteinizing H.(LH).

2- The posterior lobe or posterior pituitary (also called neurohyphysis) forms embryonic brain tissue. Thus the p.p. is a neural structure that serves an endocrine function and should be called aneuroendocrine gland. The pituitary gland is the master of the reproductive gland which any decrease or irregular secretion of it is hormone may lead to sterility. The hormone of pituitary is glycoprotiens H. and poly or oilgo peptide H. and these hormones is vary complex structure and can not be produced but it can be produced from: 1.pituitary gland of sheep, pig, horse and cattle. 2.Biological source by taken the hormone from biological fluids (blood, urine) to use clinically.  

Hormone of anterior pituitary gland Function Chemical class Hormone 1.Follicle growth 2.Estrogen release 3.spermatogenesis Glycoprotein Follicle stimulating H. (FSH) 1 1.ovulation 2.corpus lutem formation and function 3. testosterone release 4.progesteron secretion Luteinizing H.(LH) 2 1.milk synthesis 2.lactation 3.progesteron secretion and growth the CL Protein Prolactin H. (PH) 3 Growth the body tissue Growth H. (GH) 4 stimulate adrenal gland to secrete thyroxin Thyroid stimulating H. (TSH) 5 Play role in parturition Adreno cortex Oligopeptides Adreno corticotrophic H. (ACTH) 6 The 1,2,3 play important role in reproduction while the 4,5,6 is indirect in reproduction

Interaction of hormones in the female reproduction: