Henry Gray (1825–1861). Anatomy of the Human Body. 1918.
14. The Form of the Embryo at Different Stages of Its Growth
|—It is during this month that the first movements of the fetus are usually observed. The eruption of hair on the head commences, and the vernix caseosa begins to be deposited. By the end of this month the total length of the fetus, including the legs, is from 25 to 27 cm.|| 10||
|Sixth Month.—The body is covered by fine hairs (lanugo) and the deposit of vernix caseosa is considerable. The papillæ of the skin are developed and the free border of the nail projects from the corium of the dermis. Measured from vertex to heels, the total length of the fetus at the end of this month is from 30 to 32 cm.|| 11|
|Seventh Month.—The pupillary membrane atrophies and the eyelids are open. The testis descends with the vaginal sac of the peritoneum. From vertex to heels the total length at the end of the seventh month is from 35 to 36 cm. The weight is a little over three pounds.|| 12|
|Eighth Month.—The skin assumes a pink color and is now entirely coated with vernix caseosa, and the lanugo begins to disappear. Subcutaneous fat has been developed to a considerable extent, and the fetus presents a plump appearance. The total length, i. e., from head to heels, at the end of the eighth month is about 40 cm., and the weight varies between four and one-half and five and one-half pounds.|| 13|
|Ninth Month.—The lanugo has largely disappeared from the trunk. The umbilicus is almost in the middle of the body and the testes are in the scrotum. At full time the fetus weighs from six and one-half to eight pounds, and measures from head to heels about 50 cm.|| 14|