Evolution And Routes Of Immune Transmission
Károly Baintner in Intestinal Absorption of Macromolecules and Immune Transmission from Mother to Young, 2019
The yolk sac is rudimentary in the human fetus. During placentation the embryonic trophoblast cells fuse to a syncytium and invade the endometrium. The core of the chorionic villi consists of blood vessels and connective tissue and is lined by an attenuated layer of syncytiotrophoblast. In places called lacunae, not only is the uterine epithelium eliminated, but the maternal vascular epithelium as well, and the villi directly dip into the maternal blood;1572, 1573 so in these places, the maternal cellular barrier completely disappears. The syncytiotrophoblast transmits IgG from the maternal to the fetal side in the human fetus and in the rhesus,84 but relatively little antibody is transferred by the rat placenta.1177 The dog and cat (endotheliochorial placenta) also transmit small amounts of immunoglobulin prenatally; the route of transmission is very probably transplacental, but this has not been proven experimentally.154
Ultrasound in the First Trimester
Asim Kurjak in CRC Handbook of Ultrasound in Obstetrics and Gynecology, 2019
From 7 weeks of menstrual age onward, it is possible to visualize, almost constantly, a 4-to 6-mm, round cystic structure lying adjacent to the fetus, corresponding to the secondary yolk sac (Figures 22 to 24).13 It derives from the primitive yolk sac which develops from the inner cell mass on the side opposite to the amniotic cavity (Figure 3). As a result of the enlargement of the amniotic cavity, and of the transverse folding of the embryo, part of the yolk sac is incorporated into the embryo at the midgut, and the resulting secondary yolk sac is connected to the embryo by the yolk stalk or vitelline duct (Figure 8). With the continuous expansion of the amnion, the elongated yolk sac is embedded into the mesoderm of the umbilical cord, and the yolk sac is pressed against the chorion by the expanding amniotic cavity (Figure 11). It may be found generally near the point where the umbilical cord is attached to the placenta, and it is sometimes possible to confirm its extraamniotic location by visualizing both the yolk sac and the amniotic membrane on the same scan (Figure 25).
Fertilization and normal embryonic and early fetal development
Hung N. Winn, Frank A. Chervenak, Roberto Romero in Clinical Maternal-Fetal Medicine Online, 2021
Gestational sac can be visualized from the middle of the 5th week of amenorrhea as a small spherical anechoic structure placed inside one of the endometrial leafs (7). Planar mode tomograms are helpful in distinguishing early intraendome-trial gestational sac from collection of free fluid between the endometrial leafs (pseudogestational sac). The 3D sonography enables precise measurement of exponentially expanding gestational sac volume during the first trimester. At the beginning of the 5th week, small secondary yolk sac is visible as the earliest sign of the developing embryo (Fig. 15). Adjacent to the yolk sac, embryo can be seen as a small straight line when it reaches 2 to 3mm in length at the end of the 5th week.
A rare pseudo tumour in the extraembryonic coelom in first trimester of pregnancy: ultrasound and pathology
Published in Journal of Obstetrics and Gynaecology, 2019
Seiji Sumigama, Atsushi Enomoto, Satoshi Matsukawa, Takafumi Ushida, Kenji Imai, Tomoko Nakano, Tomomi Kotani, Fumitaka Kikkawa
In a review of normal early human development, there is a ‘primary yolk sac’ and ‘secondary yolk sac’ as embryological terms (Moore and Persaud 2011). At 4 weeks of gestation, there is an embryonic disc consisting of two-layered cells; embryonic epiblasts and hypoblasts. The primary yolk sac is formed from embryonic hypoblasts, and is lined with an exocoelomic (Heuser’s) membrane (cuboidal cells), outside of which is the extraembryonic mesoderm (spindle-shaped cells) (Moore and Persaud 2011; Sadler 2011). Several days later, additional cells are produced by the hypoblasts, migrate along the inside of primary yolk sac and form a new cavity, the secondary yolk sac (Sadler 2011). Until the end of 4 weeks, the primary yolk sac is pinched off and its residue is found in the extraembryonic coelom; however, it is rarely detected by ultrasonography. The ‘yolk sac’ usually detected by ultrasonography after 4 weeks is the ‘secondary yolk sac’ (Kurjak et al. 2008). In this case, the cystic mass was not observed at 4 weeks and was found at 5 weeks of gestation. The timing coincided with the formation of a residual primary yolk sac, and further, the pathological structure consistent with it. Thus, we speculated that the mass was a residual primary yolk sac that had become hyperplastic for some reason.
Renal Yolk Sac Tumor Clinically Misdiagnosed as Nephroblastoma: A Case Report
Published in Fetal and Pediatric Pathology, 2023
Meng Zhu, Chengmao Xia, Jie Yang, Zhe Liu, Xiaowen Zhao, Yaling Li, Bin Liu, Yanli Yang, Yali She
Extragonadal germ cell tumors (EGGCTs) are tumors that originate in extragonadal anatomical locations without evidence of primary gonadal origin. EGGCT includes seminoma, embryonal carcinoma, mature/immature teratoma, yolk sac tumor, and choriocarcinoma. EGGCTs composed of two or more tissue types are called mixed germ cell tumors. In 1959, a Danish pathologist, Teilum [5] described the histological morphological characteristics of yolk sac tumor for the first time, clearly pointing out that yolk sac tumor belongs to germ cell tumor, and its pathological morphology and occurrence sites are diverse. Since the basic histological characteristics of yolk sac tumor are similar to the differentiation of yolk sac during embryonic development [6], the yolk sac tumor outside the gonad may be the result of incorrect capture of germ cell precursors during embryogenesis [3]. According to this theory, yolk sac tumor can occur at any site [7].
Successful hysteroscopic treatment of a cervical heterotopic pregnancy: case report and literature review
Published in Journal of Obstetrics and Gynaecology, 2020
Antonio Rubattu, Valentina Corda, Iside Derosas, Maria Carla Monni, Cristina Nocco, Ambra Iuculano, Giangavino Peppi, Nadia Rosas, Giovanni Ruiu, Giovanni Monni
We describe the case of a 32-year-old nulliparous Caucasian woman who underwent in-vitro fertilisation (IVF) with ICSI for male factor infertility. She was referred to our centre three weeks after embryo transfer (ET) due to the suspicion of a heterotopic twin gestation with both an intrauterine and a cervical pregnancy. The β-hCG level rose appropriately from 462 to 3563 mIU/mL on days 13–17. The woman had persistent severe vaginal bleeding, however, serum β-hCG level continued to rise appropriately. On referral to our centre, a transvaginal ultrasound identified an 8 mm gestational sac with a yolk sac but without an embryo in the uterus, and a coexisting anaechoic dysmorphic area without a yolk sac inside the endocervical canal. A follow-up ultrasound the next day showed a gestational sac with a yolk sac in the cervical canal. At that time, the β-hCG level was 17,453 mIU/mL. Two days later, the scan revealed a gestational sac with a yolk sac of an increased size within the cervix. In coronal section, the intrauterine pregnancy appeared near the right tubal recess and the β-hCG level at this time was 22,255 mIU/mL. Three days after, a transvaginal ultrasound showed a heterotopic pregnancy with a viable intrauterine pregnancy consisting of an embryo with cardiac activity located in the cervix. The corresponding β-hCG level was 27,318 mIU/mL.
Related Knowledge Centers
- Endoderm
- Gastrointestinal Tract
- Gestational Sac
- Hypoblast
- Embryo
- Pregnancy
- Gestation
- Bilaminar Embryonic Disc
- Terminologia Embryologica
- Animal Embryonic Development