23.1: Introduction to the Reproductive System

Chapter Learning Objectives:

• Describe the anatomy of the male and female reproductive systems, including their accessory structures
• Explain the role of hypothalamic and pituitary hormones in male and female reproductive function
• Trace the path of a sperm cell from its initial production through fertilization of an oocyte
• Explain the events in the ovary prior to ovulation
• Describe the development and maturation of the sex organs and the emergence of secondary sex characteristics during puberty

We do not often consider that a child’s birth is proof of the healthy functioning of both the mother’s and the father’s reproductive systems. Moreover, the parents’ endocrine systems had to secrete the appropriate regulating hormones to induce the production and release of unique male and female gametes, reproductive cells containing the parents’ genetic material (one set of 23 chromosomes). The parent’s reproductive behavior had to facilitate the transfer of male gametes—the sperm—to the female reproductive tract at just the right time to encounter the female gamete, an oocyte (egg). Finally, combination of the gametes (fertilization) had to occur, followed by implantation and development. In this chapter, you will explore the male and female reproductive systems, whose healthy functioning can culminate in the powerful sound of a newborn’s first cry.  In chapter 24 we will explore the processes of embryonic and fetal development.

Figure 23.1.1: Ovulation. The male and female gametes meet in the uterine tube.  Once fertilized the ovum will finish meiosis II. (Image credit: "Blausen 0404 - Fertilization - English labels " by Blausen.com staff (2014), license: CC BY, modified by Jennifer Lange.)

Brief Overview

Before diving into the details, let's cover some basic common terms. Unique for its role in human reproduction, a gamete is a specialized sex cell carrying 23 chromosomes—one half the number in body cells. Gonads are the organs that make the gametes. Once the gametes are made, they travel in tubular structures. These structures are often the site for permanent sterilization procedures because if the gametes of the opposite sex cannot meet, then fertilization will not be possible. (Table 23.1.1) Comparing the midsagittal view of the female and male pelvis, we see multiple differences (Figure 23.1.2). Discussions on the female reproductive anatomy will be covered in section 23.3. Discussions on the male reproductive anatomy will be covered in section 23.2.

Table 23.1.1 Male and Female Reproductive Systems Comparison

Term	Male	Female
Gonads	Testes	Ovaries
Gametes	Sperm	Ova (ovum, singular, also known as eggs)
Tract Organs	Ductus deferens (or vas deferens), ejaculatory duct, urethra	Uterine tubes (or Fallopian tubes), uterus, vagina
Permanent Sterilization Procedure	Vasectomy	Tubal ligation, hysterectomy
Copulatory organ	Penis	Vagina

Figure \(\PageIndex{2}\): Reproductive System Homologues - Male and Female. Because they develop from common structures (primordial tissues) and serve a common function in adults, many of the reproductive organs are homologous between the male and the female. (Image credit: "Reproductive System Homologues - Male and Female" by Jennifer Lange is licensed under CC BY-NC-SA 4.0, modification of “Varicocele" by BruceBlaus and of "Female Reproductive System - Midsagittal" by Blausen.com staff (2014), from the Medical gallery of Blausen Medical 2014, WikiJournal of Medicine.)

Contributors and Attributions

• OpenStax Anatomy & Physiology (CC BY 4.0). Access for free at https://openstax.org/books/anatomy-and-physiology