Canal of Nuck,—is the extension of the above-named process of peritoneum into the inguinal canal. It exists in the fœtus, and is usually obliterated in the adult.

Describe the Uterine Structure. The uterine wall has 3 coats-peritoneal, muscular and mucous. Its

Peritoneal or Serous Coat,-invests the body of the organ, excepting on its lower anterior fourth.

Muscular Coat,-constitutes the chief bulk of the uterus. It consists of bundles of unstriped muscular fibres, disposed in 3 layers interlaced together; circular fibres predominating in the cervix, longitudinal fibres in the body of the organ.

Mucous Coat,-is very thick, to inch, and closely adherent to the muscular tissue, having no basement layer of connective tissue. It is covered with ciliated columnar epithelium, and studded with mucous follicles and glands, which are most numerous in the cervix. The latter, when distended by their own secretions, form sacs, which Naboth mistook for human ova, and hence were named the Ovules of Naboth. Enumerate the Uterine Vessels and Nerves. Its

Arteries, are the Uterine, from the anterior trunk of the external iliac, anastomosing with twigs from the Ovarian―(spermatic branch of the abdominal aorta).

Veins,-accompany the arteries, and in the impregnated state become sinuses. They end in the uterine plexuses.

Lymphatics,—those of the cervix end in the sacral and internal iliac glands, those of the fundus in the lumbar glands.

Nerves, are derived from the inferior hypogastric and ovarian plexuses, and from the 3d and 4th sacral nerves.

Describe the Fallopian Tubes or Oviducts. They are two tubes, each about 5 inches in length, and inch in calibre, situated in the free margin of the broad ligament, and extending from the superior angles of the uterus outwards, to terminate in free, trumpet-shaped ends, the Fimbriated Extremities, E surrounded by fringe-like processes, the Fimbria, of which one or more are attached to the ovary of that side. Their structure is similar to that of the uterus, their mucous lining being continuous with the uterine mucous membrane and with the peritoneum. They open by one end into the uterus at its cornua, by the other end into the peritoneal cavity.

What are the Ovaries? Two oval bodies,F of whitish color, situated in the broad ligament, behind and below the Fallopian tubes, one on each side of the uterus, to which they are attached by the Ligaments of the Ovaries.H

They each measure about 11⁄2 inch by 34 by, and are invested by peritoneum, except posteriorly.

Describe the Structure of the Ovaries. They are composed of a vascular stroma containing the Graafian Vesicles or Ovisacs, in various stages of development, and are surrounded by a dense fibrous coat, the Tunica Albu ginea.

Describe the Graafian Vesicles. They are the ovisacs containing the human ova, are very numerous (about 70,000 in each ovary), vary in diameter from to inch, but after puberty a few are found of from to inch or Each vesicle presents an―

more.

External Coat,-of fibro-vascular structure.

Ovi-capsule,-
-or internal coat.

Membrana Granulosa,—a layer of nucleated cells, which at one point are heaped up around the ovum in a mature vesicle, forming the Discus Proligerus.

Fluid,-of transparent, albuminous character, containing the ovum in immature vesicles.

What is the Ovum? It is a spherical mass of protoplasm, about inch in diameter when fully developed. It presents a—

Vitelline Membrane,—also called the Zona Pellucida,- —a colorless envelope, in which is contained the

Vitellus or Yelk,-composed of granules in a fluid substance, one of which is called the

Germinal Vesicle,-which contains a smaller body named the Germinal Spot, measuring about the g of an inch in diameter.

What is the Corpus Luteum? It is a puckered yellow spot in the substance of the ovary, produced as a result of the rupture of a Graafian vesicle and the discharge of an ovum, probably by the fatty degeneration of the extravasated blood.

The

True Corpus Luteum,—is that of pregnancy, and may increase in size, not disappearing until full term.

False Corpus Luteum,—occurs when impregnation has not taken place, and is absorbed in about three months.

What is the Pampiniform Plexus? A venous plexus near the ovary, formed by the veins of that organ.

Enumerate the Arteries and Nerves of the Ovaries.

Their

Arteries,-are the Ovarian (or Spermatic), from the aorta, which also supply the Fallopian tubes, anastomosing with the uterine arteries.

Nerves, are derived from the Spermatic plexus.

What is the Parovarium? The Parovarium, or Organ of Rosenmüller, is a group of tubules, situated in the broad ligament, between the ovary and the Fallopian tube, and converging to a large duct, the Duct of Gartner, which ramifies in the broad ligament, and descends along the side of the uterus. It is thought to be a remnant of the Wolffian Body of foetal life. (See "Reproduction," in COMPEND OF PHYSIOLOGY.)

FIG. 95.

THE MAMME.

Describe the Mammæ. The breasts are two hemispherical eminences, situated one on each latero-anterior aspect of the chest, extending from the sternum to the axilla, and from the 3d rib to the 7th. Each breast contains the Mammary Gland and is surmounted by the Nipple, around the base of which is a zone of colored cutaneous tissue, the Areola, pink in virgins, darker in women who have borne children. In the male the mammæ are rudimentary organs, but capable of development under special circumstances.

Describe the Structure of the Mammary Gland. It is a compound conglomerate gland, composed of 15 or 20 lobes and their ducts, with a packing of areolar and adipose tissue, and enveloped by a fibrous capsule which forms septa between the lobes. Each lobe is made up of lobules, 2 and these again are formed by the aggregation of the Acini or terminal vesicles, in which the milk is secreted. The

Tubuli Lactiferi or Tubuli Galactophori,1-are the excretory ducts of the lobes, one for each. They are formed by the junction of the ducts from each lobule, and converge towards the areola, beneath which they form Ampullæ or dilatations, and thence, piercing the nipple, open on its summit by separate orifices.

What is the Circulus Venosus? An anastomotic venous circle around the base of the nipple, from which larger veins run outwards and terminate in the axillary and internal mammary veins.

Name the Arteries of the Mammæ. They are derived from the Thoracic Branches of the axillary, the Intercostals, and the Internal Mammary arteries.

THE ORGANS OF SENSE.

THE SKIN AND ITS APPENDAGES.

Name the Divisions of the Skin. It is divided into the-
Superficial Epithelial layers.

Epidermis, or Cuticle, Rete Mucosum, the pigmentary layers.

Derma, or Cutis Vera, the True Skin.

Papillary Layer,c next below the rete, from which it is separated by a homogeneous basement membrane.

Corium,d the deepest portion.

What Structures lie in and beneath the Skin? The

Sensitive Papilla, containing the Tactile Corpuscles in very sensitive parts,

FIG. 96.

Describe the Structure of the Epidermis. It is an unorganized epithelial structure, having no vessels or nerves. The cells of which it is composed are agglutinated together in a laminated arrangement, are flat and dry on the surface, round and softer in the central portion, columnar and softest in the deepest layers. The lowest and softest layers are named theRete Mucosum,-which is closely moulded upon the papillary layer of the derma, and contains pig. ment cells, to which the color of the skin is due.

Describe the Structure of the Derma. The true skin is a highly organized, tough yet elastic tissue, and serves to protect the parts beneath, to perform the functions of excretion and absorption, and as the chief seat of the sense of touch. It consists of fibro-areolar tissue, vessels and nerves. The

M

Papillary Layer,-situated next to the rete mucosum, is covered with minute conical elevations (papillæ), inch high inch in diameter at their base, very numerous and arranged in parallel curved lines wherever sensibility is greatest. Each papilla contains a capillary loop or plexus, the termination of one or more sensory nerves,—and in highly sensitive parts, an oval-shaped body, the Tactile Corpuscle.

Corium, the lower layer of the derma, is composed chiefly of interlacing bundles of white fibrous tissue, in which are mingled some yellow elastic fibres, also plain muscular fibres wherever hairs are found,—and lymphatic vessels, blood-vessels and nerves, in plexiform arrangement. Describe the Nails. They are flat, horny structures, a modification of the epidermis, molded upon the derma at the dorsal surface of the terminal phalanges of both fingers and toes. Each nail is convex on its outward surface, and is imbedded by its Root into a fold of the skin. Its

Matrix-is that portion of the derma directly beneath the nail. It is covered with highly vascular papillæ. The

Lunula,-is a white crescentic portion of the nail nearest to its root, produced by the diminution in number and size of the papillæ beneath. What are the Hairs? They are also a modified form of the epidermis, found over nearly the whole surface of the body, much varied in size and color. Each hair consists of a Root and a Shaft. The-

Root,-is lodged in an involution of the epidermis called the Hair-follicle,

which sometimes extends into the subcutaneous cellular tissue. The root rests on a vascular papilla at the bottom or Bulb of the follicle, which supplies it with the material for its growth.

Shaft, is the projecting portion of the hair. It consists of a medulla in the centre, next a fibrous portion, externally a cortex of thin, flat scales. The finest hairs have no medulla.

Point, consists of the fibrous portion and the cortex, the medulla being wanting.

Where are the Sebaceous Glands most abundant? In the scalp, the face, around the anus, and the apertures of the nose, mouth and external ear. The largest are the—

Meibomian Glands,-situated in the eyelids (see Fig. 104).

Describe the Sebaceous Glands. They are small, glandular bodies situated in the corium or in the subcutaneous cellular tissue over most of the body, but not in that of the palmar surface of the hands nor on the plantar surface of the feet. Each gland consists of a single sacculated duct, usually opening into a hair follicle, but sometimes ending on the surface of the integument.