REPRODUCTION AND DEVELOPMENT INTRODUCTION

Abstract

Publisher Summary This chapter focuses on reproduction and development. The hypothalamus has both “tonic” and “cyclic” controls over the release of gonadotropic hormones (GTH) in the rat. The tonic control resides within the arcuate–median eminence region, and it is responsible for the basal release of GTH. The cyclic control is present within the pre-optic-suprachiasmatic region, and it is responsible for the preovulatory release of the luteinizing hormone (LH) and the follicle stimulating hormone (FSH). Cell bodies of luteinizing hormone-releasing hormone (LH–RH) neurons reside in the pre-optic area and suprachiasmatic nucleus, which synthesize LH–RH. Thereafter, LH–RH is transported via axons of these cells to be stored within their terminals within the median eminence. The newly accumulated ME–LHRH is released to induce preovulatory LH and FSH surges. Two independent systems are involved in the preovulatory surge of GTH on proestrus: (1) a system that manufactures newly releasable LHRH and (2) the catecholamines system, which triggers the release of the newly synthesized LHRH.