扬子鳄胚胎背腺的发生及退化

本文在１４例扬子鳄Ａｌｌｉｇａｔｏｒｓｉｎｅｎｓｉｓ胚胎中观察了背腺的发生及退化过程。孵化第２８天,背中线左右两侧第二行鳞片处的表皮内陷形成实心的背腺腺芽;第３８天,背腺腺泡明显,腺上皮为复层上皮;从第４６天开始,腺上皮出现明显的退化,大量增殖的腺管上皮细胞逐渐堵塞腺管及腺孔。扫描电镜观察表明,孵化第３２—３６天的胚胎背部第二行鳞的各列鳞片表面均有背腺腺孔,以后逐渐出现少数不规则的退化,孵化第５８天以后,绝大多数背腺腺孔消失。对扬子鳄背腺的发生及退化现象作了讨论。     

Cellular analysis on localization of lens forming potency in the newt iris epithelium

The localization of a lens forming potency in the iris epithelium was studied by autoradiographic analysis of the distribution of ³H-thymidine labelled cells to be participated in lens regeneration in newts. DNA synthesis started from the dorsal portion of the iris epithelium around 4 days after lentectomy. 5 days after lentectomy, a large number of labelled cells were mostly found in the dorsal sector, showing strong contrast to the ventral and lateral sectors of iris, which contained a few labelled cells. The labelled index (the number of labelled cells/the number of cells in the definite pigmented area of the iris epithelium) of the dorsal sector attained the highest value, 29.7 ± 2.35, on day 7 after lentectomy, and dropped temporarily. This was followed by the second peak on day 12. The dorso-ventral ratio of the labelled index reached to the highest value, 6.87 ± 0.67, on day 5. This ratio decreased rapidly after the completion of a lens rudiment, and it became about 1. In “chase” experiments by diluting the radio-isotope with excess cold thymidine, it was obviously shown that most of the cells labelled with the radio-isotope and distributed in the dorsal marginal iris 5 days after lentectomy participated in the formation of a lens regenerate during the period of chasing. From these results, the following conclusion was drawn. The iris epithelium consists of at least 2 different cell populations; one is capable of transformation into lens cells and is distributed mostly in the dorsal portion of the iris epithelium, while the other has no potency for transformation and is able to grow to compensate a loss of the dorsal marginal cells which transformed into lens cells during the process of lens regeneration.     

The development of the tongue in the chick embryo: observation under a scanning electron microscope

The morphological features of the chick embryo tongue from the 8th day of incubation till hatching and during the early post incubation period have been investigated by means of Scanning Electron Microscope. At the SEM, it is possible to observe that already at the 8th day of incubation, the body and the root are separated by a low smooth-surfaced ridge. In the following days this ridge develops, giving rise to the so-called lingual spines, whose significance is still uncertain. As concerns the evolutive pattern of the superficial layer of the epithelium, in the first days of the considered incubation period the cells appear dome-shaped and have microvilli on their apical surface; afterwards they tend to become more flattened, and the microvilli are replaced by a thick net of microplicae. In the last days of incubation and after hatching desquamative phenomena become evident. The above described evolutive process can be regarded as a common feature of the whole dorsal lingual surface; only few regional differences are to be noted, such as the earlier development of the microplicae on the apex and borders of the tongue. In particular, the microplicae observed at the apex of the tongue show a typical aspect and arrangement; they run regularly parallel to each other. On the lingual dorsal surface taste bud-like structures have never been observed.     

Histochemical detection of sugar residues in the chick embryo mesonephros with lectin-horseradish peroxidase conjugates

Summary Fragments of mesonephros were taken from chick embryos and studied from the 4th to the 21st day of incubation. A battery of seven different horseradish peroxidase-labelled lectins was used to study the distribution of carbohydrate residues in glycoconjugates along the mesonephric nephron during the period of excretory activity and the period of involution. ConA and WGA reacted at every site of the nephron thus showing the ubiquitous presence of -D-mannose andN-acetyl-d-glucosamine. SBA was a good marker of the proximal tubule. Other lectins, such as PNA and LTA, reacted only for a short time at some sites during the considered period of incubation. The presence of sialic acid was detected in the podocytes, capillary wall and mesangial cells. From the 10th-11th day of incubation changes were noted in the proximal tubule as shown by PNA reactivity. This may be significant as regards the exact stage of incubation during which the involution of mesonephros begins.     

Histochemical and quantitative study of the cloacal glands of Triturus marmoratus marmoratus (Amphibia: Salamandridae)

The cloacal glands of the male marbled newt Triturus marmoratus marmoratus were studied during winter and summer by histochemical and quantitative histologic methods. Four types of glands were distinguished: pelvic, dorsal, ventral, and Kingsbury's glands. The pelvic and dorsal glands have an eosinophilic epithelium and secrete neutral mucins. The ventral and Kingsbury's glands have a basophilic epithelium and secrete acid mucins. The lectin-histochemical characterization of the carbohydrates secreted by the four gland types revealed that the secretion of both the pelvic and Kingsbury's glands contain β-GalNAc in the peripheral region of the oligosaccharide, and that the dorsal glands secrete a glycoprotein with α-GalNAc. The ventral gland sections did not react to any of the lectins used here. The quantitative study revealed that the cloaca undergoes seasonal variations in volume, being significantly larger in winter than in summer. The total volume occupied by both the pelvic and ventral glands, as well as their tubular diameter, are also significantly greater in winter, while these parameters do not vary in dorsal and Kingsbury's glands. No seasonal differences were observed in the height of the epithelium in any gland     

Histochemical detection of sugar residues in the chick embryo mesonephros with lectin-horseradish peroxidase conjugates

Fragments of mesonephros were taken from chick embryos and studied from the 4th to the 21st day of incubation. A battery of seven different horseradish peroxidase-labelled lectins was used to study the distribution of carbohydrate residues in glycoconjugates along the mesonephric nephron during the period of excretory activity and the period of involution. ConA and WGA reacted at every site of the nephron thus showing the ubiquitous presence of alpha-D-mannose and N-acetyl-D-glucosamine. SBA was a good marker of the proximal tubule. Other lectins, such as PNA and LTA, reacted only for a short time at some sites during the considered period of incubation. The presence of sialic acid was detected in the podocytes, capillary wall and mesangial cells. From the 10th-11th day of incubation changes were noted in the proximal tubule as shown by PNA reactivity. This may be significant as regards the exact stage of incubation during which the involution of mesonephros begins.     

Histochemical analysis of goblet cell mucins in the chick embryo colon

The histochemical characteristics of colonic epithelial mucins were investigated in the chick embryo. At the 14th day of incubation it was possible to demonstrate the presence of glycogen. At the 15th day a few epithelial cells showed the presence of neutral and sialylated mucins. On the 16th day, also sulfated secretory material was detectable together with neutral and sialylated mucins in cells with the typical shape of goblet cells. From the 17th day to the 20th day of incubation the two types of acid mucins appeared in some cells to be placed in distinct zones of the supranuclear cytoplasm. At the 21st day, neutral, sialylated and sulfated mucins were all present in the majority of goblet cells, which were found mainly in the epithelium lining the crypts.     

Morphology, and muscle- and papilla-volume ratios, of the tongue of Laudakia stellio (Agamidae, Squamata): a histological and stereological study

We examined the histological structure of the tongue of Laudakia stellio, the starred agama lizard (Agamidae, Squamata), under light microscopy. We also investigated the muscle and papilla volume ratios, with volumes of each aspect of interest estimated according to the Cavalieri method. The macroscopically short, thick and muscle-rich front tip of the tongue of L. stellio does not show any bifurcation, and under light microscopy, the oval-shaped papilla-free front tip was seen to be covered by keratinized stratified epithelium. The dorsal and ventral parts were different, with the former partially covered by keratinized stratified epithelium and rich in secretory glands and secretory cells. The ventral part, which contained keratinized stratified cells, had a flat surface with no papillae. The dorsal surface of the anterior and posterior parts contained fungiform papillae, with the apical parts of these papillae containing minimal keratin; the interpapillar space was covered by keratin-free squamous stratified epithelium. The middle section of the tongue contained cylindrical-type papillae, with serous and mucous secretory glands and ducts at their base. Finally, the frontal and middle parts of the ventral and dorsal surfaces did not contain any taste buds, although there were some in the hind part of the dorsal surface. As morphometric estimates of volumes of the muscles and papillae, the mean volume ratios (relative to total tongue volume)+/-standard deviation were 0.66+/-0.03 and 0.33+/-0.03, with mean coefficients of error of 0.02 and 0.03, respectively.     

Beta-keratin expression in avian tongue cell aggregates.

Rotation-mediated aggregation was used to test the capacity of early embryonic tongue cells from different regions of the tongue to reorganize histotypically and terminally differentiate in vitro. Cells dissociated from the anterior ventral (AV) or posterior ventral (PV) surface of the 12 day embryonic tongue were cultured 6 days, fixed, and embedded in paraffin. Indirect immunofluorescence microscopy was used to demonstrate the occurrence and distribution of beta-keratins, the presence of which represented regional and differentiation specific markers of late tongue development. Aggregates of AV cells were organized into a beta-keratin-producing stratified epithelium. Similar PV aggregates formed only an alpha-keratin-producing stratified epithelium. The epithelial cells of these tongue tissues constructs expressed alpha- and beta-keratins in a manner consistent with the temporal and histotypical expression of keratins observed in vivo.     

Kinetics of cell replacement in the stratum granulosum of mouse tongue epithelium

Sheet preparations of the stratum granulosum from the epithelium of the ventral surface of mouse tongue permit examination of cell replacement of this maturation compartment of the tissue. The cell transit rate/day is related to the cell desquamation rate and the cell production rate. The latter is approximately 6500-8000 cells/mm2/day, suggesting a 4-5-fold greater turnover compared with mouse dorsal skin epithelium. The use of [3H]IUdR and [3H]TdR at different times of day provides evidence for a reutilization of label from [3H]TdR released during nuclear degradation in the stratum granulosum. Flooding with unlabelled thymidine is not effective in suppressing this reutilization.     

Development of the tongue and taste disks in Pelobates fuscus

In the tadpole of Pelobates fuscus the process of tongue formation starts at the 32nd developmental stage. In more advanced stages (older than 38th) fast anterior and faucial growth of the tongue fold has been observed. This process is accompanied by the development of the gustatory organs. The dorsal surface of the tongue fold, smooth at the beginning, in older tadpoles (developmental stages 36-39th) forms protrusions in which gustatory organs of the taste disk type (TDs) develop. In the 41 st tadpole developmental stage anlages of TDs are formed by elongated cells, located more or less perpendicularly to the surface of the tongue. The diameter of the sensory area of a TD at the 45th developmental stage amounts to 94 microm, while in metamorphosed individuals it reaches 130-140 microm. At the base of a TD the presence of basal cell morphologically similar to that of Merkel cell was observed at the 42nd developmental stage of a tadpole. Fully developed afferent synaptic connections in the sensory epithelium of a TD were found starting from the 44th developmental stage. Single synaptic vesicles with an electron-dense core were observed in gustatory cells as early as at the 41 st developmental stage of the tadpole. From the observations reported here it can be inferred that in Pelobates fuscus development of both the tongue and TDs is similar to that already described in the representatives of the Rana genus.     

Effect of axotomy on cholinergic enzyme activities in the spinal cord and sciatic nerve of the dog

Choline acetyltransferase (ChAT) and acetylcholinesterase (AChE) activity measured in the ventral and dorsal part of the dog spinal cord (L6-S2) and in the stumps of the sciatic nerve 5, 10, 15 and 21 days after its transection were compared with the corresponding activities in the intact contralateral nerve and in sham-operated animals. AChE was also examined histochemically. Changes in the enzyme activities in the central nerve stump were correlated with activity changes in the spinal cord. In the central nerve stump, a marked (25%) increase in AChE activity was found on the fifth day after transection, but by the 21st day it fell below control value levels; up to the 15th day it showed good correlation with AChE activity in the ventral spinal cord. Histochemically, pronounced reduction of enzymatic activity was found in the ipsilateral part of the spinal cord. On the 15th day, ChAT activity in the ventral spinal cord was also significantly decreased and the accumulation of the enzyme in the central nerve stump was negligible. On the contrary, at the last 21-day interval examined, a significant increase in ChAT activity and a nonsignificant increase in AChE activity was found in the spinal cord, but their activities in the central nerve stump were decreased. In the degenerated peripheral nerve stump ChAT activity dropped by an average of 99% and AChE activity by 48% during the first 15 days after transection but, on the 21st day, AChE activity was 22% higher than at the preceding interval.     

Morphogenesis of rat lingual filiform papillae.

The morphogenesis of filiform papillae on rat tongue was investigated with the electron microscope. Tongue rudiments were first seen on the 12th day of gestation. At 15-17 days, dermal papillae had formed and were arranged in hexagonal array on the dorsal lingual surface. Capping each dermal papilla was a two-layered epithelium that protruded slightly above the lingual surface, thus forming the early filiform papilla. In the next stage of development, at 18-19 days of gestation, the epithelium lining the papilla had differentiated into two cell populations, one producing hard keratin, the other producing soft keratin. Some of the keratinized epithelial cells assumed a position at an acute angle to the tongue surface and extended deep into the epithelium. In the next stage, 20-21 days, a cleft appeared within these angularly oriented cells. This resulted in the division of the epithelium into keraatin-lined individual filiform papillae. Finally, the individual papillae increased in size to the adult form.     

Kinetics of Cell Replacement In the Stratum Granulosum of Mouse Tongue Epithelium

Abstract. Sheet preparations of the stratum granulosum from the epithelium of the ventral surface of mouse tongue permit examination of cell replacement of this maturation compartment of the tissue. the cell transit rate/day is related to the cell desquamation rate and the cell production rate. the latter is approximately 6500-8000 cells/mm²/day, suggesting a 4-5-fold greater turnover compared with mouse dorsal skin epithelium. the use of [³H]IUdR and [³H]TdR at different times of day provides evidence for a reutilization of label from [³H]TdR released during nuclear degradation in the stratum granulosum. Flooding with unlabelled thymidine is not effective in suppressing this reutilization.     

Ontogenetical development of the chick and duck subcommissural organ. An immunocytochemical study

The ontogenetical development of the subcommissural organ (SCO) was investigated in chick embryos collected daily from the 1st to the 21st day in incubation. Some duck embryos, and adult chickens and ducks were also studied. Immunocytochemistry using an anti-Reissner's fiber (RF) serum as the primary antibody was the principal method used. In the chick embryos the events occurring at different days of incubation were: day 3 morphologically undifferentiated cells in the dorsal diencephalon displayed immunoreactive material (IRM); days 4 to 6 immunoreactive cells proliferated, formed a multilayered structure and developed processes which traversed the growing posterior commissure and ended at the brain surface; day 7 blood vessels penetrated the SCO, scarce hypendymal cells appeared, the first signs of ventricular release of IRM were noticed, appearance of IRM bound to cells of the floor of the Sylvius aqueduct; day 7 to 10 the number of apical granules and amount of extracellular IRM increased progressively; day 11 RF was observed along the Sylvian aqueduct, day 12 RF was present in the lumbar spinal cord; day 13 IRM on the aqueductal floor disappeared; days 10 to 21 hypendymal cells proliferated, developed processes and migrated dorsally, ependymal processes elongated and their endings covered the external limiting membrane. In adult specimens the ependymal cells lacked basal processes and the external membrane was contacted by hypendymal cells. the duck SCO appears to follow a similar pattern of development.     

Cytokeratin expression in human tongue epithelium.

The epithelium of the human tongue shows diverse morphological variations from one site to another and even within the epithelium of the same papilla. This complexity has led to confusion regarding tongue epithelium as being orthokeratinized, parakeratinized, or nonkeratinized. Cytokeratins have been shown to characterize different epithelia. The present paper describes cytokeratin expression by adult tongue epithelia and relates their distribution to morphology. Six healthy human tongue specimens were obtained after plastic surgery and cytokeratin expression was investigated immunohistochemically, using a panel of 15 antibodies for cytoskeletal proteins, and biochemically using two-dimensional gel electrophoresis. The results showed that the ventral and lateral surfaces of the tongue are related to the nonkeratinizing stratified squamous epithelia, esophageal type, whereas the dorsal surface showed mixed expression of cytokeratins. In the tip of filiform and on the surface of fungiform papillae, cytokeratins of terminal differentiation are expressed as skin type; and in the rest of the papillae as well as in interpapillary areas, the epithelium expresses esophageal type cytokeratins. Certain simple epithelial cytokeratins were found in taste buds. Cytokeratin 19 was also detected in the basal cell layer of all esophageal type epithelia in the tongue. The present results provide basis for studies on the biological events in epithelial differentiation during development and in pathology.     

The expression of receptivity markers in the fallopian tube epithelium

Pinopodes represent the morphological and integrins, the biomollecular markers of endometrial receptivity. We studied using scanning electron microscopy, the expression of pinopodes on tubal samples and their corresponding endometria, from 21 women of reproductive age (7 from proliferative phase, 7 from day LH +5 and 7 from day LH +7). In addition, we examined the immunohistochemical staining of integrins αvβ3, αvβ5 and their ligands, fibronectin (FN) and osteopontin (OPN) in the same tubal epithelium samples. Pinopodes were detected on the tubal epithelium exclusively during day LH +7, coincident with their formation in the endometrium and synchronous to αvβ3 sharp increase in the oviduct epithelium, suggesting a regulation similar to the endometrium. In contrast, αvβ5, FN and OPN remained unchanged during the cycle. These results show for the first time the formation of pinopodes in the tubal epithelium at the time of endometrial receptivity and correlate it with the upregulation of the intact dimmer αvβ3 in the tubes.     

Cyclopamine and jervine in embryonic rat tongue cultures demonstrate a role for Shh signaling in taste papilla development and patterning: fungiform papillae double in number and form in novel locations in dorsal lingual epithelium

From time of embryonic emergence, the gustatory papilla types on the mammalian tongue have stereotypic anterior and posterior tongue locations. Furthermore, on anterior tongue, the fungiform papillae are patterned in rows. Among the many molecules that have potential roles in regulating papilla location and pattern, Sonic hedgehog (Shh) has been localized within early tongue and developing papillae. We used an embryonic, tongue organ culture system that retains temporal, spatial, and molecular characteristics of in vivo taste papilla morphogenesis and patterning to study the role of Shh in taste papilla development. Tongues from gestational day 14 rat embryos, when papillae are just beginning to emerge on dorsal tongue, were maintained in organ culture for 2 days. The steroidal alkaloids, cyclopamine and jervine, that specifically disrupt the Shh signaling pathway, or a Shh-blocking antibody were added to the standard culture medium. Controls included tongues cultured in the standard medium alone, and with addition of solanidine, an alkaloid that resembles cyclopamine structurally but that does not disrupt Shh signaling. In cultures with cyclopamine, jervine, or blocking antibody, fungiform papilla numbers doubled on the dorsal tongue with a distribution that essentially eliminated inter-papilla regions, compared with tongues in standard medium or solanidine. In addition, fungiform papillae developed on posterior oral tongue, just in front of and beside the single circumvallate papilla, regions where fungiform papillae do not typically develop. The Shh protein was in all fungiform papillae in embryonic tongues, and tongue cultures with standard medium or cyclopamine, and was conspicuously localized in the basement membrane region of the papillae. Ptc protein had a similar distribution to Shh, although the immunoproduct was more diffuse. Fungiform papillae did not develop on pharyngeal or ventral tongue in cyclopamine and jervine cultures, or in the tongue midline furrow, nor was development of the single circumvallate papilla altered. The results demonstrate a prominent role for Shh in fungiform papilla induction and patterning and indicate differences in morphogenetic control of fungiform and circumvallate papilla development and numbers. Furthermore, a previously unknown, broad competence of dorsal lingual epithelium to form fungiform papillae on both anterior and posterior oral tongue is revealed.     

Development of spontaneous motility in chick embryos. Interaction of strychnine, glycine and GABA.

The interaction of strychnine (1 mg/kg egg weight), glycine (100 mg/kg egg weight) and GABA (103 mg/kg egg weight) on spontaneous motor activity recorded by the method of Kovach (1970) in intact eggs was studied in chick embryos from the 11th to 21st day of incubation. In 11- and 13-day embryos, neither of the amino acids influenced strychnine activation of spontaneous motility. From the 15th incubation day, strychnine activation was distinctly affected by both amino acids, but the maximum effect was observed on the 19th day. Glycine had a stronger inhibitory effect, since it prevented strychnine convulsions from developing, whereas GABA only modified them. It can be concluded from the results that glycine-sensitive and GABA-sensitive mechanisms of embryonal spontaneous motility do not begin to take effect in chick embryos until the 15th day of incubation.