Chapter 6 Opener Human blastocyst (at right) emerging from its zona pelucida

Figure 6.1 An unfertilized ovum

Figure 6.2 Maturation of sperm

Figure 6.2 Maturation of sperm

Figure 6.3 Fertilization and production of the conceptus

Figure 6.3 Fertilization and production of the conceptus

Figure 6.4 Development of the human conceptus

Figure 6.5 Blastocyst in the process of implanting itself

Figure 6.6 Stages of prenatal development

Figure 6.7 Alfred Jost’s experiments on rabbits

Figure 6.8 The genetic basis of sex determination

Box 6.1 Biology of Sex: Atypical Development: Chromosomal Anomalies

Figure 6.9 Sex determination

Box 6.2 Biology of Sex: Atypical Development: Gonadal Intersexuality

Figure 6.10 Migrating germ cells

Figure 6.11 Development of the male and female reproductive tracts

Figure 6.11 Development of the male and female reproductive tracts

Box 6.3 Biology of Sex: Atypical Development: Androgen Insensitivity Syndrome

Figure 6.12 Development of the male and female external genitalia

Figure 6.12 Development of the male and female external genitalia (Part 1)

Figure 6.12 Development of the male and female external genitalia (Part 2)

Figure 6.12 Development of the male and female external genitalia (Part 3)

Box 6.4 Biology of Sex: Atypical Development: Congenital Adrenal Hyperplasia

Figure 6.13 Descent of the testes

Figure 6.13 Descent of the testes

Figure 6.13 Descent of the testes (Part 1)

Figure 6.13 Descent of the testes (Part 2)

Box 6.5 Biology of Sex: Atypical Development: 5α-Reductase Deficiency

Box 6.6 Biology of Sex: Atypical Development: Hypospadias and Micropenis

Figure 6.14 The third interstitial nucleus of the anterior hypothalamus (INAH3)

Figure 6.15 Sexual differentiation in the hypothalamus

Figure 6.15 Sexual differentiation in the hypothalamus

Figure 6.16 Copulating rats

Figure 6.17 Hormones and sexual behavior in rats

Figure 6.17 Hormones and sexual behavior in rats

Figure 6.18 When monkeys copulate, the male often grasps the feet or legs of the female with his own feet

Photo, p. 177 1957 advertisement for DES in a medical journal

Photo, p. 178 Because of variations in the timing of puberty, these 12-year-old girls vary a great deal in their physical development

Figure 6.19 Growth velocity curves for boys and girls

Figure 6.20 Typical development of pubic hair in girls at puberty

Figure 6.21 Typical development of breasts in girls at puberty

Figure 6.22 Puberty is starting earlier

Figure 6.23 Typical development of male external genitalia at puberty

Figure 6.24 Hormonal control of puberty

Figure 6.24 Hormonal control of puberty

Box 6.7 Biology of Sex: Atypical Development: Precocious and Delayed Puberty

Figure 6.25 MRI slice through the human brain showing some of the regions whose size is affected by sex hormone levels at puberty

Box 6.8 Personal Points of View: My Life with Androgen Insensitivity Syndrome