Biological Development

Preadolescence is a short period that immediately precedes adolescence. It is marked by a growth spurt that can begin at 10 years of age for girls and 13 years of age for boys. It is distinguished by puberty, the stage at which the reproductive organs become functional and secondary sex characteristics develop. Both genders produce male hormones, androgens, and female hormones, estrogens, in comparatively equal amounts during childhood. At puberty, the hypothalamus of the brain signals the pituitary gland to stimulate other endocrine glands—the adrenals and the ovaries or testes—to secrete their hormones directly into the bloodstream in differing proportions (more androgens in boys and more estrogens in girls).

The age at which puberty takes place varies and is about 2 years earlier in girls than in boys. In both genders, it is preceded by spurts in height and weight. Overall, girls stop growing sooner and have smaller increases in height and weight than boys. During the pubertal growth spurt, weight increases 50%; this varies according to pubertal maturation, degree of adiposity, and size of muscle mass. During puberty, the growth spurt results in a 15% to 20% increase in height. The adolescent’s general appearance tends to be awkward—long-legged and gangling. This growth characteristic is termed asynchrony because different body parts mature at different rates. The sweat glands are very active, and greasy skin and acne are common. Both genders mature earlier, grow taller, and are heavier than adolescents in past generations.

The development of secondary sexual maturation can be assessed using Tanner staging. Stages are based on breast and pubic hair development for girls and genital and pubic hair development for boys (Table 10-1). Development (growth and sexual maturation) is predictable but variable. Tanner staging provides a more accurate assessment of a child’s development than chronologic age (James and Ashwill, 2007). In most girls, changes in the breast with the development of a small bud of breast tissue (thelarche) signals the earliest sign of puberty. The average age is 11 years. Menarche (onset of menstrual periods) occurs approximately 2 years afterward. Menarche can range from to 15 years and still be within normal guidelines. According to Hockenberry and Wilson (2007), girls’ peak height velocity occurs at about 12 years of age (6 to 12 months before menarche); girls gain 2 to 8 inches in height and 15 to 55 pounds during adolescence. In addition to secondary sex characteristics becoming more apparent before menarche, fat is deposited in the hips and thighs, causing them to enlarge. Hair grows in the pubic area and underarms. The body reaches its adult measurements about 3 years after the onset of puberty. At this time, the ends of the long bones knit securely to their shafts and further growth can no longer take place.

Table 10-1

Sexual Maturation Rating (SMR): Tanner Stages

Boys
Stage 1	Stage 2	Stage 3	Stage 4	Stage 5
Pubic hair: none Penis: preadolescent Testes: preadolescent	Pubic hair: slight, long, straight, slightly pigmented at the base of the penis Penis: slight enlargement Testes: enlarged scrotum, pink, slight alteration in texture	Pubic hair: darker in color, starts to curl, small amount Penis: longer Testes: larger	Pubic hair: coarse, curly, similar to adult but less quantity Penis: larger, glans and breadth increase in size Testes: larger, scrotum darker	Pubic hair: adult distribution spread to inner thighs Penis: adult in size and shape Testes: adult
	Early puberty: Testes,  yr; penis,  yr; pubic hair,  yr
		Middle puberty: Testes,  yr; penis,  yr; pubic hair,  yr
			Late puberty: Testes,  yr; penis,  yr; pubic hair,  yr
Breast Development in Girls*
Stage 1	Stage 2	Stage 3	Stage 4	Stage 5
Preadolescent	Breast bud stage (thelarche): breast and papilla elevated as small mound, areolar diameter increased	Breast and areola enlarged, no contour separation	Areola and papilla form secondary mound	Mature, nipple projects, areola part of general breast contour
	Early puberty: 9-13 yr
		Middle puberty: 12-13 yr
			Late puberty: 14-17 yr*
Pubic Hair Development in Girls
Stage 1	Stage 2	Stage 3	Stage 4	Stage 5
Preadolescent (none)	Sparse, lightly pigmented, straight medial border of labia	Darker, coarser, beginning to curl, increased over pubis	Coarse, curly, less in amount than adult, typical female triangle	Adult female triangle, adult quantity spread to medial surface of thighs
	Early puberty:  yr
		Middle puberty:  yr
			Late puberty:  yr

^*Breast and pubic hair development may continue into late adolescence and increase with pregnancy.

Modified from Tanner, J. M. (1962). Growth at adolescence (2nd ed.). Oxford: Blackwell Scientific Publications; Marshall, W. A., and Tanner, J. (1969). Variations in pattern of pubertal changes in girls. Arch Dis Child, 44(235), 291-303. Modified with permission from Blackwell Scientific Publications and The BMJ Publishing Group.

Although breast cancer is rare in adolescents, this is a time when girls are aware of their bodies and breast self-examination should be introduced. Breast self-examination should be routinely performed beginning at 18 to 21 years of age (Fallat et al., 2008). The American Cancer Society provides various informational pamphlets describing the procedure.

The first sign of puberty in boys is usually the enlargement of the testes, which begins between and 14 years of age. Ejaculation and the appearance of pubic hair occur approximately 1 year after this. The production of sperm begins between and years of age. Complete fertility is not present at this time, but impregnation is possible. According to Hockenberry and Wilson (2007), boys’ peak height velocity occurs at around 14 years of age, followed by growth of the testes and penis. The penis elongates and widens, testes enlarge, and scrotum pigment becomes evident. Both axillary and facial hair increase, along with body odor. Voice changes are also noticeable. By late adolescence (17 to 21 years of age), adult genitalia is attained. The male voice deepens, and most linear growth is achieved. Overall, boys gain 4 to 12 inches in height; weight gain is between 15 and 65 pounds during adolescence.

The American Cancer Society recommends that boys examine their testes during or after a hot bath or shower. Each testicle is examined with the index and middle finger of both hands on the underside of the testicle and the thumbs on the top of the testicle. It is normal for one testicle to be larger than the other. The testicles are gently rolled between the thumb and finger. Testicular self-examinations are performed once a month. If a lump is discovered, it should be reported immediately. Males also need to report an abnormal enlargement of a testicle or a heavy feeling in the scrotum. In addition, they should report any pain or discomfort in a testicle or in the scrotum, especially if symptoms last as long as 2 weeks.

Developmental Theories

Adolescents are in a period of transition from childhood to adulthood (Table 10-2). Erik Erikson identified the major task of this group as identity formation versus role confusion. At this time, children must determine who they are, where they are going, and how they are getting there. This should not imply that adolescents wait until this stage to develop individuation. The child has been developing autonomy since toddlerhood.