Fetuses Of Various Gestational Ages Research Articles

Cytological, Histochemical, and Ultrastructural Study of the Human Fetal Spleen of Various Gestational Age With Future Implications in Splenic Transplantation: An Anatomical Perspective.

Purpose: The spleen is a fist-sized largest lymphoid organ located in the left hypochondrium. It has a unique location, embryological and histological structure that differs significantly from other lymphoid organs. The present work was undertaken to study the microscopic and ultramicroscopic histogenesis patterns of the spleen in relation to gestational age.Methods: The splenic tissue of nine aborted fetuses of various gestational ages was studied. For cytology study, special stains like Masson’s trichrome, Periodic Acid-Schiff, and Reticulin were used; immunohistochemical staining was performed with triple antibodies (C-myc, Ki-67, and Ber-H2); and for ultrastructure study, aluminum mounted specimens coated with gold and argon gas were observed under scanning electron microscopy (SEM).Results: Microscopy and immunohistochemistry showed the developmental changes in the spleen from the emergence of the primordium to the end of the embryonic period in all stages of fetogenesis. The spleen primordium of a fetus at the developmental stage of the primary vascular reticulum was seen in the first trimester fetuses. The primordium is comprised mainly of mesenchymal tissue; numerous lymphocytes invading the area surrounding the central artery forming the periarterial lymphoid sheaths (PALS) were seen surrounded by venous sinuses in the early second trimester fetuses.Conclusion: The organizational changes in the reticuloendothelial system and microstructure of the spleen during fetogenesis are very crucial to achieving adult morphology in the future. Histogenesis of the fetal spleen follows a multistep process depending upon the gestational age. Any deviation from normalcy may lead to structural and functional abnormality later in life.

Immunohistochemical Assessment of Hassall's Corpuscles in Human Foetal Thymuses

ObjectiveHassall's corpuscles are unique component of the thymic medulla, which participate in the physiological activities of the thymus. Although, they have role in maturation and differentiation of thymocytes, their function still remains an enigma. Present study proposes immunohistochemical criteria for assessing structural and functional characteristics of Hassall's corpuscles using antibodies against cytokeratin markers in human fetuses.MethodsHassall's corpuscles of 30 aborted human fetuses of various gestational ages (12 to 31 weeks) were studied by using CK5, CK8 and CK14 antibodies.ResultsHassall's corpuscles exhibited positivity for CK5, CK8 from 13 weeks onwards, while CK14 positivity was seen after 16 weeks. CK8 and CK14 positivity was seen around the periphery, while CK5 positivity was observed both at peripheral and central part of Hassall's corpuscles. Two major growth spurts were observed after 16 and 22 weeks of gestation.ConclusionsDemonstration of CK5, CK8 and CK14 (markers for simple and stratified epithelium) in Hassall's corpuscles from thymic medulla of human fetuses support the hypothesis that thymus undergoes sequential stages of differentiation similar to the epidermal tissue. This study enriches the information about structural and functional aspects of Hassall's bodies. This knowledge is crucial and can be used to treat various immunodeficiency diseases of skin and thymic tissue by acquiring progenitor stem cells from fetal thymic tissue.Support or Funding InformationDirector PGIMER, Chandigarh

Morphological variants of lateral meniscus of the knee: a cadaveric study in South Indian human fetuses

In the present study, the objectives were to study the morphology of the lateral menisci (LMs) in human fetuses from a South Indian population and to verify the developmental etiology of the discoid lateral meniscus (DLM). The study included 106 fetal knee joints which were fixed in 10% formalin. After dissecting the joints, the morphological variants of the shapes of the LMs were macroscopically noted and classified as discoid and nondiscoid. The nondiscoids were subdivided into C-shaped and crescentic. The discoid lateral menisci (DLMs) were divided into complete and incomplete discoid. From our observations, 82.1% of the LMs were found to be nondiscoid. Among them, 62.3% were C-shaped and 19.8% were crescentic. The remaining 17.9% of the LMs had a discoid shape, and among these, 14.1% were incomplete discoid and 3.8% were completely discoid. Bilaterality of the discoid shape was observed in 26.6% of the cases. There was a female preponderance (11:8) among LMs with discoid morphology. In conclusion, the prevalence of DLM according to the present study was estimated as 17.9%. Our findings favor Kaplan's theory, as the majority of the fetuses of various gestational ages had nondiscoid LMs. Even the youngest fetus (CRL 88mm, 14weeks of gestation) exhibited a lateral tibial plateau that was incompletely covered by the meniscus, which did not exhibit a discoid shape. We believe that the DLM is anomalous and arises through variant morphogenesis.

Stereological investigation and expression of calcium-binding proteins in developing human inferior colliculus

The mammalian inferior colliculus (IC) is a major relay nucleus in the auditory pathway. Prenatal development of the human IC has been inadequately studied. The present study reports the morphometric development and maturation of the human IC using unbiased stereology, in 18 aborted fetuses of various gestational ages (12–29 weeks) and two babies aged 40 postnatal days (PND) and 5 months (that died of postoperative complications). It also demonstrates the functional maturation of the IC by examining the expression of calcium-binding proteins – parvalbumin (PV) and calbindin (CB). There was a significant increase in the total number of neurons and glia from 18 weeks of gestation (WG). The glia and neuron volume increased significantly from 16 WG to 22 WG, respectively. The total volume of IC also increased significantly from 18 WG onwards. On the other hand, the number and volume of undifferentiated cell bodies across all ages decreased significantly. Expression of CB was concentrated in the dorsal cortex while that of PV was mainly confined to the central nucleus of the IC, possibly indicating an early segregation of parallel processing of information in the auditory pathways. Intense staining for CB in the soma and dendrites appeared earlier than that of the PV. The morphological maturation appeared to overlap the onset of functional maturation suggesting an activity-dependent mechanism in the development of IC.

AT4 receptor binding in the developing rabbit.

The binding of the AT(4)-specific analog, divalinal-AngIV (Dival), was studied in rabbit fetuses of various gestational ages. Saturation isotherm and competition data from selected tissues indicate that fetal Dival binding sites are saturable and specific for AT(4) ligands. Autoradiographs revealed that binding was present in all the specimens examined. The peripheral nerves, kidneys, and heart were particularly heavily labeled. Labeling of some tissues, such as forming bones, was not constant as gestational age increased. Other tissues, including multilocular fat, sinus hairs, and enamel organs of nascent teeth, exhibited substantial binding as these tissues developed.

Dorsoventral patterning in oesophageal atresia with tracheo-oesophageal fistula: Evidence from a new mouse model

Background/Purpose: The well-established Adriamycin rat model of oesophageal atresia (OA) and tracheo-oesophageal fistula (TOF) complements recently described mouse genetic models in which loss of function mutations in foregut patterning genes, such as Nkx2.1 (Ttf 1), lead to OA/TOF. The authors aimed to integrate the 2 systems by adapting the Adriamycin model to the mouse to study molecular aspects of tracheo-oesophageal development. Methods: Pregnant CBA/Ca mice were injected intraperitoneally with 4 mg/kg of Adriamycin on embryonic days 7.5 and 8.5. Embryos and fetuses of various gestational ages were subjected to morphologic or histologic examination. Sections were stained with H & E or processed for immunohistochemistry using an antibody specific for Nkx2.1. Results: Tracheo-oesophageal malformations were observed in 47% of Adriamycin-treated embryos. Early foregut development was similar in Adriamycin-exposed and control embryos but, by E11.5, many treated embryos had an undivided oesophago-trachea, which gave rise to the lung buds and a fistula to the stomach. The fistula originated from the dorsal aspect of the undivided tube and was negative for Nkx2.1, or showed only transient Nkx2.1 expression, compared to the strongly positive bronchi ventrally. Conclusions: The Adriamycin model of OA is adaptable to the mouse. In the absence of tracheo-oesophageal separation, the dorsal fistula retains its nonrespiratory commitment suggesting that dorsoventral patterning of foregut development is undisturbed by Adriamycin exposure. J Pediatr Surg 37:185-191. Copyright © 2002 by W.B. Saunders Company.

Fetal hematopoiesis during first and second trimester of pregnancy: relevance for in utero stem cell transplantation.

In-utero stem cell transplantation (IUST) is an intriguing alternative to postnatal transplantation of hematopoietic stem cells. However, despite decades of research, both in animal models and in human fetuses, the clinical application of IUST is still not feasible. Thus far, more than 30 case reports on clinical experience with IUST in the human fetus, for various indications, have been published or described (Table 1). These cases were treated with cells from fetuses of various gestational ages and with different quantity and quality of stem cells. Only a few cases of IUST in severe combined immunodeficiency (SCID) showed some degree of engraftment. A potential cause of failure of IUST is lack of engraftment due to competition of the transplant with a vigorous hematopoietic compartment in the host. Not only differences in the characteristics of stem cells used can influence engraftment, but also characteristics of stem cells present in the host at each specific gestational age have to be taken into account. During embryonic and fetal life, the major hematopoietic sites of hematopoiesis change (Fig. 1). We have summarized the literature on the hematopoietic compartment of the first and second trimester fetus and discussed it in relation to IUST.

The development of noradrenaline-, acetylcholinesterase-, neuropeptide Y- and vasoactive intestinal polypeptide-containing nerves in human cerebral arteries

The development of cerebrovascular nerves containing noradrenaline (NA), acetylcholinesterase (AChE), neuropeptide Y (NPY) and vasoactive intestinal polypeptide (VIP) in the basilar artery was histochemically or immunohistochemically studied in human fetuses of various gestational ages. At the 12th week of gestation, nerve fibers containing NA and AChE appeared. Both types of nerve fibers consisted exclusively of the longitudinal nerve fibers (LNF) running along the basilar arteries. Subsequently, the circular nerve fibers (CNF) gradually increased and such development was then completed by the 20th week of gestation. NPY- and VIP-containing nerve fibers were detected in human fetal cerebral arteries in the 16th week of gestation, in the form of LNF. Subsequently, CNF gradually increased and development was completed by the 24th week of gestation. These results indicate that neuropeptide-containing nerve fibers, together with NA- and AChE-containing nerves, therefore contribute to the control of cerebral circulation in the later stages of embryogenesis in human cerebral arteries.

Pancreatic Amylase Expression in Human Pancreatic Development

Enzymatic and immunologic methods were used to study amylase expression in amniotic fluid and human pancreatic tissue from fetuses of various gestational ages. A starch-coated slide assay was used to quantitate amylase activity in amniotic fluids, and samples with activity were studied by electrophoresis to determine the presence of salivary amylase (Amy1) and pancreatic amylase (Amy2) isozymes. Immunohistochemical studies were performed with both a rabbit anti-human Amy1 antibody and a murine anti-human Amy2 antibody (Amy2/SP2/1). Amy2/SP2/1 was used to discriminate between Amy1 and Amy2. Both Amy1 and Amy2 activities were present in amniotic fluid from 14 weeks' gestation, and immunologic activity was present in pancreatic tissue sections from 15.9 weeks' gestation.

Expression of gastrointestinal carcinoma-associated antigen (GICA) detected in human fetal tissues by monoclonal antibody NS-19-9.

The expression of a gastrointestinal carcinoma-associated antigen (GICA), a monosialoganglioside, was investigated in tissues from human fetuses of various gestational ages (10-40 weeks). Mouse monoclonal antibody NS-19-9, generated in mice immunized with SW1116 human colon carcinoma cells, was used along with a second polyclonal antibody to mouse IgG to detect antigen expression as visualized by means of the biotin-avidin-peroxidase assay. Sections of snap-frozen tissues or tissues fixed in 4% formaldehyde, in mercury chloride-formaldehyde, or in Bouin's solution were used. GICA was consistently detected in the mucosal epithelium of the small intestine. In contrast, the mucosal epithelium of the colon-rectum contained no detectable GICA, nor could the antigen be detected biochemically in extracts from the large intestine. GICA was usually found in the epithelium of the larynx, trachea and main bronchi as well as in the conjunctiva, lacrimal and salivary glands, gall bladder and ductus choledochus, and in the epithelium of the renal pelvis of early and mid-gestation fetuses.

The bovine allantoic and amniotic epithelia. SEM and TEM studies.

The ectodermal and endodermal coverings of the allanto-amniotic membrane in cattle fetuses of various gestational ages have been studied by scanning and transmission electron microscopy. We have observed that the allantoic and amniotic epithelia have rather similar cells which are rich in filaments but poor in organelles. Neither epithelium reflects its different origin nor the differences in the composition of the two fetal fluids. Maturation changes occur in the pattern of the various surface specializations until midterm. Coral-like luminal outgrowths, which also contain organelles, were observed in both epithelia, whereas microplicae had formed only on fully differentiated amniotic cells. Interspersed smooth-surface cells in the allantoic epithelium that differ also in nuclear shape, glycocalyx, and mitochondria are regarded as a second cell type. Besides fluid-filled blisters and cornified pustules, the most typical feature of the amniotic epithelium is a rather regular lateral cell interdigitation with tongue-like lamellae of even thickness. Micropinocytotic vesicles are more frequent than in the allantois. Both epithelia possess similar tight junctions; no morphological or histochemical indications of an active sodium transport were evidenced.

Pathogenicity studies on a bovine herpesvirus

A virus was isolated from uterine exudate of a cow and later identified as a herpesvirus that had no serologic relationship to several known viruses. The virus produced a febril response in 7 month old Holstein steers. Inoculation of the virus into bovine fetuses of various gestational ages resulted in death of some fetuses in the 3rd and 4th months of gestation. Some fetuses in the 3rd and 4th month, and all older than 4 months, survived the inoculation. These fetuses experienced a lymphoreticular activation and a humoral antibody response.

Developmental changes of free amino acids in bovine fetal fluids with gestational age and the interrelationships between the amino acid concentrations in the fluid compartments.

Thirty ninhydrin-positive compounds were determined in the sera, amniotic fluid, stomach content and allantoic fluid from 29 bovine fetuses of various gestational ages. Fetal serum was found to contain about 3-fold higher concentrations of free amino acids (FAA) than maternal serum, and allantoic fluid contained about 3-fold higher concentration of FAA than fetal serum. Decreasing concentrations of FAA were found in serum as a function of the crown-rump length for the amino acids taurine, aspartic acid, threonine, serine, ornithine and lysine. Decreasing concentrations of FAA in allantoic fluid were found for threonine, alanine and ornithine, whereas increasing concentrations were found for phosphoserine and methionine as a function of the crown-rump length. Correlations were found between the concentrations of most amino acids in amniotic fluid and stomach content, but fewer correlations were found between the other fluid compartments. The transport of amino acids between compartments is discussed.

Hemoglobin A synthesis in the developing fetus.

Abstract To determine when synthesis of hemoglobin A (composed of 2 α and 2 β chains and the hemoglobin predominant in the human adult) begins in the fetus, hemoglobin synthesis was measured in fetuses of various gestational ages. Synthesis of hemoglobin A by reticulocytes obtained from 42 embryos and fetuses 3.5 to 20.0 cm in crown-to-rump length accounted for 4.3 to 13.0 per cent of total hemoglobin synthesis, and varied directly with fetal crown-to-rump length. Since the smallest embryo was estimated to be 55 days old, β-chain synthesis has begun by that gestational age. Furthermore, since β thalassemia is characterized by decreased β-chain synthesis, the accurate diagnosis of this condition in fetuses depends on knowledge of the values for hemoglobin A synthesis in normal fetuses of variousgestational ages. (N Engl J Med 289:58–62, 1973)

Demonstration of a Receptor Reserve for Acetylcholine in the Human Fetus

AbstractThe development of the acetylcholine (ACh) receptor function in man was studied by means of determination of dose‐effect curves for ACh action upon fetal smooth muscle tension in vitro. Segments of ileum from human fetuses of various gestational ages (6.5–20.5 cm head‐rump length) were used. Phenoxybenzamine (POB) blocked irreversibly the spasmogenic action of ACh. Exposure of the tissue to low concentrations of POB for a short period led to a shift of the subsequent dose‐effect curve for ACh along the dose‐axis. By varying the length of the POB exposure period (4–10 min) different degrees of shift, i.e. different degrees of antagonism, could be produced. It was found that the shift could amount to as much as about one logarithmic unit with preserved maximum of the dose‐effect curves. This means that activation of only a fraction of ACh receptors is enough for maximal response. Thus, the phenomenon of “receptor reserve” to ACh was demonstrated. Furthermore, the extent of this “reserve” was not significantly changing during the fetal age period studied. It is concluded that the characteristics of ACh receptor function in man are fully developed in early fetal life.

Demonstration of a receptor reserve for acetylcholine in the human fetus.

The development of the acetylcholine (ACh) receptor function in man was studied by means of determination of dose-effect curves for ACh action upon fetal smooth muscle tension in vitro. Segments of ileum from human fetuses of various gestational ages (6.5–20.5 cm head-rump length) were used. Phenoxybenzamine (POB) blocked irreversibly the spasmogenic action of ACh. Exposure of the tissue to low concentrations of POB for a short period led to a shift of the subsequent dose-effect curve for ACh along the dose-axis. By varying the length of the POB exposure period (4–10 min) different degrees of shift, i.e. different degrees of antagonism, could be produced. It was found that the shift could amount to as much as about one logarithmic unit with preserved maximum of the dose-effect curves. This means that activation of only a fraction of ACh receptors is enough for maximal response. Thus, the phenomenon of “receptor reserve” to ACh was demonstrated. Furthermore, the extent of this “reserve” was not significantly changing during the fetal age period studied. It is concluded that the characteristics of ACh receptor function in man are fully developed in early fetal life.