RMRJ4KF2–. Chordate anatomy. Chordata; Anatomy, Comparative. 330 CHORDATE ANATOMY The most important, if not the exclusive, endocrinal secretion of the thyroid gland is an iodine compound, thyroxine, the empirical chemical formula for which is C15H11O4NI4. A substance with identical properties has been made synthetically, and it is generally the synthetic drug which is used in medical practice.. Fig. 293. CONNECTIVE VjO .''''TISSUE COLLOID '•Jj BLOOD VESSEL FOLLICLE .CUBOIDAL EPITHELIUM -A portion of a section of the thyroid gland, enlarged, showing the secretory epithelium and the colloid-filled folli
RMRHKNP8–. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 300 M. K. MONTGOMERY AND M. McFALL-NGAI vjmr i>'-'- ftl. Figure 4. Transmission electron micrograph of the light organ of a juvenile 24 h post-hatch. The crypts, populated with bacterial symbionts. are lined with a simple cuboidal epithelium whose apical surface bears an extensive brush border of microvilli. This epithelial cell layer is surrounded by a layer ot blood vessels and connective tissue. The reflector is composed of several layers of electron-dense platelets, and is immediately adjacent to the ink sac whose in
RMRHK5M6–. Biology of the laboratory mouse. Mice as laboratory animals; Mice; Animals, Laboratory; Mice. HISTOLOGY 145 hematoxylin-eosin stains. The cells rest on a well developed basement membrane. Occasionally the gland may be distended and contain large central cavities into which the tubules and acini open directly. In the lower part of the body a duct lined by cuboidal epithelium is present which anasto- moses with the central ducts of the gland lobules of the tail. The gland lobules of the tail are composed of small alveoli lined by low columnar cells which have dark, round nuclei near the base a
RMRJ6YK7–. Chordate morphology. Morphology (Animals); Chordata. Figure 8-3. Development of the human epidermis and hair follicle. A, epidermis of 2.1 -mm embryo; B, epidermis of 16-mm embryo; C, epidermis of 32-mm embryo; D, epidermis of 85-mm embryo; E to H, progressive stages in the development of the follicle and hair. (After Patten, 1946) of the snout. It is not strengthened by a bony core as in the cow but is seated on a bony knob of the skull. The pointed tip is produced and maintained by wear. Bmbryological development The ectoderm is at first a simple cuboidal epithelium which gradually becomes
RMRJ4KEK–. Chordate anatomy. Chordata; Anatomy, Comparative. Fig. 293. CONNECTIVE VjO .''''TISSUE COLLOID '•Jj BLOOD VESSEL FOLLICLE .CUBOIDAL EPITHELIUM -A portion of a section of the thyroid gland, enlarged, showing the secretory epithelium and the colloid-filled follicles.. Fig. 294.—Longitudinal section of head of 19-day Petromyzon embryo showing the relation of the thyroid anlage to the floor of the pharynx, ch, optic chiasma; ep, epiphysial outgrowth; h, hypophysial ingrowth; mcs, mesenteron; n, nasal epithelium; nc, notochord; oc, oral cavity; op, oral plate; sc, canal of spinal cord; th, thyroi
RMRHN5WR–. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. »Cu - ';- :-V^&. FIGURE 2. Light micrograph of a sagittal section through a brooding operculum showing the columnar epithelium (CIE) bordering the opercular pore (OP), cuboidal epithelium (CbE), cuticle ( C'u). and embryos (Em) within the brood chamber. Scale equals 20 /j.. FIGURE 3. A thin section through the apical region of the columnar epithelium bordering the pore of a brooding operculum. Note the narrow diameter of the epithelial cells, the long microvilli (Mv) penetrating the filamentous cuticle (Cu), and a portio
RMRJ6YJT–. Chordate morphology. Morphology (Animals); Chordata. Figure 8-3. Development of the human epidermis and hair follicle. A, epidermis of 2.1 -mm embryo; B, epidermis of 16-mm embryo; C, epidermis of 32-mm embryo; D, epidermis of 85-mm embryo; E to H, progressive stages in the development of the follicle and hair. (After Patten, 1946) of the snout. It is not strengthened by a bony core as in the cow but is seated on a bony knob of the skull. The pointed tip is produced and maintained by wear. Bmbryological development The ectoderm is at first a simple cuboidal epithelium which gradually becomes
RMRHKM1D–. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. OYSTERS EXPOSED TO A DINOFLAGELLATE 325. Figure 9. Juvenile oysters. Sections of paraffin-embedded animals are stained with hematoxylin and eosin. (Bar = 40 Mm-) (A) A positive control animal (fed 100% T-ISO) shows moderate columnar absorptive cells) 1) and star-shaped lumens (2). (B) Starved juveniles show cuboidal epithelium (1) with dilated, rounded lumens (2). (C) Most EXUV-fed animals showed high-columnar epithelium with foamy cytoplasm (1) and small lumens (2). (D) Some EXUV-fed animals showed low-columnar epi- thelium
RMRN5060–. Anatomy, descriptive and applied. Anatomy. Fig. 1174.—Diagrammatic representation of the female reproductive organs and their relations to the bladder and urethra, lateral view. (Toldt.) Structure (Figs. 1175, 1176, and 1184).—The ovary consists of the cortex and medulla, in the former of which are founi) the Graafian follicles and theu- remains and the hilum of the ovary. The cortex consists of stroma and Graafian follicles. Peripherally, the stroma is condensed to form a capsule, the tunica albuginea, which is covered by a layer of cuboidal epithelial cells called the germinal epithelium,
RMRJ50EG–. The chordates. Chordata. 304 Basic Structure of Vertebrates Simple Epithelium. An epithelium only one cell in thickness is termed simple. There is, however, great variation in the thickness of simple epithelia. The cells, seen in sections perpendicular to the sur- face, may be approximately square in outline. Such an epithelium is called cuboidal (Fig. 243), but incorrectly, for the cells are usually hexagonal prisms. A simple epithelium consisting of tall prismatic cells (Figs. 244C, 245) is called columnar. At the extreme of thinness are epithelia (flat or squamous) each of whose cells is
RMRHNXGP–. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. SWIMBLADDER OF THE TOADFISH 175 erally the gas gland is continuous with the cuboidal, apparently non-glandular, epithelium of the roof of the anterior chamber. The gas gland is most strongly developed and heavily folded within a few millimeters of the retia mirabilia (Fig, 3). At a distance from the retia the degree of folding dwindles rapidly and the glandular cells become smaller. The glandular epithelium is everywhere only one cell thick. The cells are columnar with a dense cytoplasm stained red by azan. An interesting fe
RMRHP59N–. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 220 KALI1! I J. BAILKY apparatus is a deep Mask-shaped pit with a thickened sensory epithelium at the base. Thickened sensory areas are also to be found in the lining of the canals and ampulke of the ear. A cross-section of the pharynx shows distinct gill bars which, with the exception of the last, hear no filaments. Medial to the gill bars along the ventral aorta the thyroid appears. consisting of .scattered follicles full of colloid. The viscera have changed somewhat; the gall bladder which earlier was lined with cuboidal
RMRHN9TT–. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 182 ABBY SCHWARZ it extended as two tongue-shaped masses running posteriorly along the lateral walls almost to the end of the cavity. In these places the epithelium was unfolded and each cell appeared to be in contact with a rete vessel. Intra- and intercellular vacuoles were present. Caudally there was a slight decrease in the size of the cuboidal cells. The tongue-shaped masses tapered slightly at their caudal ends. The dorsal wall was almost uniformly thin, exhibiting only one layer of squamous cells, but the ventral wall
RMRHNXFP–. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. RESPONSE OF URODELES TO TSH 57 mognathus, on the other hand, show more individual variation but all present an appearance of moderate to relatively high activity : cuboidal to columnar epithelium ; less homogeneous, often basophilic. colloid; relatively abundant chromophobe droplets at the peripheries of the colloid masses (Fig. 2 ). Administration of TSH caused marked changes in the thyroid in both. Thy- roids of animals given seven injections (over a 13-day period) and fixed 24 hours after the last injection showed the max
RMRHMM2R–. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. EFFECTS OF COPPER ON THE BARNACLE 439 A. Planktonic cyprids Whole mounts of planktonic cyprids treated with D.T.O. show characteristic greenish-black precipitate of copper in the following sites (Fig. 1) : 1. In ovoid to cuboidal vacuoles within the loose connective tissue underlying the postero-lateral carapace. 2. In shapeless masses in the connective tissues of the antero-ventral region. 3. In the epithelium lining the stomach. 4. In the epithelium lining the posterior two-thirds of the hind-gut. The lateral copper-contai
RMRHN2A8–. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. CIDAROID DIRECT DEVELOPMENT 99. Figure 1. Early development of Pliyllacunthus parvispinus. whole mounts of fixed and live embryos, a. 16 cell fixed embryo (3 h). The first four cleavages are equal, b. Approximately 30-cell live embryo (3.5 h). Note blastomeres are of different sizes, c. Live wrinkled blastula (11.5 h). At this stage, the wrinkles are decreasing in number. The embryo is still inside the fertilization envelope. (Fig. 3a). At this stage, the epithelium is composed of cuboidal cells. Over the next several hours,
RMRH046G–. Bulletin. Science. CAUDAL SPINE REPLACEMENT IN ROUND STINGRAYS 121 â » Ec band. Fig. 3. Photomicrographs of primordial spine bud in the round stingray, a) A cross section of the dorsal surface of the tail of Urobatis halleri showing a developing spine primordium. The inserted boxes (b-d) indicate areas that are shown in figures 3b-d at higher magnification. Outer layer of ectoderm (Ec); endoderm (En); cuboidal ectoderm (Cu); ectodermally-derived pseudostratified colum- nar epithelium (Pe); mesodermally-derived pseudostratified columnar epithelium (Pm); mesenchymal- like cells (Mc); enameloi
RMRHN5PP–. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. * ' o * t ;:, ? Bin <$?£:£&• ' ? • '•, V 0 - ' 0 n °o 0 t 'f * ^. .^5# ^••r.ffe jQ-%".^> iTt^^)^^ ->3%^ C FIGURE 7. A section through the inner ( IE) and outer (OE) cuboidal epithelial layers adjacent to the columnar pore epithelium of a brooding operculum showing outer cuticle (Cu), microvilli (Mv), pigment granules (P), and basal intercellular space (Bin). Note that the intracellular vacuoles (IVa) are larger and more abundant in the outer as compared with the inner epithelium. Scale equals 2 p. The in
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