Liver development in the rat and in man during the embryonic period (Carnegie stages 11-23).

Hepatic structures appearing during embryonic Carnegie stages 11-23 were analyzed and compared in OFA-IOPS rat and human embryos. The group of rats--crown-rump length (CRL) 2-16 mm, 10-16 days postcoitus--was composed of 127 specimens (52 of stages 11-12, 55 of stages 13-19, and 20 of stages 20-23), the human group of 9 embryos at stages 14-23--CRL 5-31 mm, age 32-57 days--and human stages 11-13 were described according to former literature. The specimens were subjected to serial histological sections with graphic reconstructions. In both series, stage 11 was characterized by hepatic diverticulum development, stage 12 and thereafter by cellular differentiation (septum transversum giving the liver stroma and hepatic diverticulum the hepatic trabeculae), and stage 13 by epithelial cord proliferation enmeshing stromal capillaries. From stage 14, the hepatic gland and its vascular channels presented considerable enlargement while hematopoietic function appeared. From this stage, the development of cystic primordium, never present in rat, was constant in man. At stage 18, after a period of obturation due to epithelial proliferation, the bile ducts became reorganized and ensured the continuity between liver cells and gut. From stages 18 to 23, biliary ductules developed in periportal connective tissue producing ductal plates that received biliary capillaries. Except for gallbladder, similarity and presence of the same hepatic structures in man and rat during the embryonic period stages 11-23 permit us to consider the rat as a good experimental model for liver development, for example, in studies on teratology and congenital anomalies.

Ultrasonic and histopathological correlations of deep focal hepatic lesions induced by stereotaxic Nd-YAG laser applications.

Thirty six deep focal hepatic lesions were induced in eleven piglets by means of an Nd-YAG laser. Laser shots of 80 W power and 10 s duration were used, the beam being transmitted through an echoguided stereotaxic handpiece. From day 0 to day 120, the animals underwent ultrasonographic and morphological controls. At lasering time an hyperechoic image--12-18 mm in diameter--appeared due to boiling of tissue water. During the twenty postoperative days the lesion core was an echo-free area due to tissue vaporization, surrounded by an hyperechoic ring of increasing fibrosis, containing neovascularization and biliary ductules, while the hypoechoic outer area represented the peripheral halo of edema. In the long term, hyperechoic structures--swollen fibrotic septa of homogeneous fibrotic network--invaded the lesion site confirming good healing.

[Histological aspects of congestive cardiomyopathy caused by alcohol. Comparison with so-called primary cardiomyopathies]. / Aspects histologiques de la cardiomyopathie congestive d'origine èthylique. Comparaison avec les cardiomyopathies dites primitives.

The endoventricular biopsies of nine patients with alcoholic congestive cardiomyopathy were studied under the light microscope and under the electron microscope. These were compared with the results of nine cases of primary congestive cardiomyopathy, at a similar clinical stage. In the absence of specific signs, the overall appearance on both light and electron microscopy is sufficiently suggestive to allow differentiation of the two forms of cardiomyopathy. Repeated biopsies revealed disappearance of the nuclear abnormalities after withdrawal of alcohol, which introduces a prognostic element.

Comparison of the liver and biliary duct development in man and in the rat at the end of the embryonic period.

Hepatic and biliary structures present during embryonic Carnegie stage 23 were analyzed and compared in OFA-IOPS rat and human embryos. The group of embryos was composed of 3 rat specimens-crown rump length (CRL) 16 mm, age 16 days 5 hours post coltus- and of 1 human embryo- CRL 31 mm, age 57 days PC-. The specimens were submitted to serial histological sections with graphic reconstruction. In both species, the basic architecture of liver parenchyma was established including parenchymal cords or plates alternating with hepatic sinusoids. Veinous channels were clearly defined. The intrahepatic biliary system, referred as ductal plates (DP) developed into the periportal connective tissue while the portal spaces were not yet existing. DP was recognized either as a single layered cuboidal structure or as a double layered one dilated to form mature tubular ducts. The latter layout was more frequent in the rat. Except for gallbladder which is never present in the rat, similarity and presence of the same hepatic structure in both species at the end of the embryonic period (stage 23) suggest that the rat is a good experimental model for liver development and will be useful to understand the mechanism of congenital anomalies and specially the involvement of ductal plates in the congenital diseases of intrahepatic bile ducts.

[Argon laser and microarterial soldering]. / Laser argon et soudure micro artérielle.

Fifty Wistar rats were submitted to a carotid end-to-end microanastomosis by means of a Coherent 900 Argon Laser. The laser shots were of 300 mW in power output and 5 sec. in duration with an impact area of 150 microns in diameter. The anastomosis was obtained in 4 min. using on an average 19 impacts. The luminal patency was evaluated through doppler and angiography visualization regularly achieved from day 0 up to 7 months. Light, scanning electron microscopic and ultrastructural examinations revealed that, on day 0, endothelial damages never exceeded 100 microns in width in the vicinity of the anastomotic line. Collagenous denaturation was immediately observed in the media and adventitia. The fusion line became re-endothelialized from day 3 and a collagenous network was always present in the media on day 10. Furthermore a slight fibrosis of the adventitia increased the wall resistance. The patency rate was 76% complications such as disruption and aneurysm were due to the initial technical drawbacks.

[Influence of pedicle clamping in partial hepatic resection with the Nd YAG laser. Comparative study in a series of 15 pigs]. / Influence du clampage pédiculaire dans les résections hépatiques partielles au laser YAG Nd. Etude comparative sur une série de 15 porcs.

Liver resection is performed in 15 pigs by means of low divergent Nd YAG laser, the hepatic pedicle being clamped and not. Clamping does not modify the efficiency of laser hemostasis during resection but increases the thickness of the ischemic layer underlying the cut liver edge. The coagulation necrosis and the edematous layer are more thickened. Migration of inflammatory cells and young fibrosis present at day 3 are gaining ground until day 15. During the same period, biliary neoductules and nodules of hepatic regeneration appear. Hepatic inflow being conserved, these reactions are delayed and less intensive. The hyperthermia, the inflammatory cellular reaction and the deepness of parenchymal damages induces by pedicle clamping are suitable for antitumoral surgery. Cooling effects of hepatic inflow are better for traumatic surgery.

[Partial splenic resections and Nd-YAG laser]. / Résections partielles de rate et laser YAG-Nd.

Eleven partial splenectomies are performed in pigs. Simultaneous section and hemostasis are obtained with continuous 80 W power shoot. There is no hemorrhagic or septic complication and normal splenic weight is recovered in 5 months. Platelets elevation observed in post-operative. Platelets elevation observed in post-operative period returns to normal rate between 20th and 30th day. Acute cellular damage of cut splenic edge does not exceed 3 mm in thickness. Semi-thick and electron microscopic examination reveals at day 10 mitotic figures of lymphocytes (i.e. splenic regeneration) and at day 30 high density of mast cells and plasmocytes i.e. cellular biostimulation).

[Deep and localized hyperthermia of the liver induced by stereotaxic Nd-YAG laser irradiation]. / Hyperthermie profonde et localisée du foie par irradiation stéréotaxique au laser YAG-ND.

Thirty six hepatic lesions (12-18 mm) of localized hyperthermia are induced in eleven pigs by means of a Nd-YAG laser. Laser shots of 80 W/10 sec. are transmitted through a stereotaxic handpiece coupled to a water cooling circulation protecting the optic fibre. The handpiece placement is performed through an ultrasound-guided trocar. The efficiency of the irradiation is visualized by immediate temperature increasing, by ultrasonographic imaging and by anatomical verifications from operating time to four months. The center of lesion initially occupied by coagulative necrosis is rapidly marginated by a gaining ground fibrosis. At long term a fibrotic network invades the scar and confirms healing free of complications. This ultrasonographically assisted technique is proposed for deep vaporisation of disseminated hepatic metastases.

[Hepatic resections using an Nd YAG laser. Anatomic and biological results of an experimental study]. / Résections hépatiques au laser YAG Nd. Résultats anatomiques et biologiques d'une étude expérimentale.

Experimental hepatic resections were performed with a Nd YAG laser in 32 New-Zealand rabbits. The beam was simply transmitted by a quartz fiber of 4 degrees 2 and 8 degrees in divergence for the full angle, without any focalization. Section was possible at a power output superior to 20 W requiring short cutting time. Complete hemostasis was obtained as long as the diameter of encountered vessels did not exceed 4,5 mm. Immediately after resection the parenchyma was covered by an ischemic layer varying from 2 to 8 mm. Its thickness rapidly increased to high levels whenever the power output exceeded 40 W or when hepatic pedicle was clamped. Healing process was installed at day 30. There was no hemorrhagic, biliary or septic complication. Eleven animals were alive eight months after. Histological examination revealed four layers: a first one of carbonization, a second of condensed cells, a third of edema presenting disruption of sinusoids, and a fourth one composed of progressively normal tissue. Peripherical veins presented thrombosis of their blood content and coagulative necrosis of their wall while bile canaliculi were preserved. Fibrosis appeared in the edematous layer the 10th day and was completely formed at day 30. Electron microscopic examination revealed shadowy cells embedded in the condensed layer and mitochondrial alteration in the edematous layer. The 15th day foci of cell regenerations were registered. High levels of SGOT, SGPT and LDH (fractions IV and V) were observed immediately after resection.(ABSTRACT TRUNCATED AT 250 WORDS)

[Round cells of human sperm]. / Les "cellules rondes" du sperme humain.

Many round cells are found whose number may become conspicuous. These cells may originate as well from germinal as from somatic lines. Electron microscopy is the only way to distinguish the two kinds of origin. In some specimens germinal cells predominate (spermattids, plurinuclear cells), in others there are many phagocytic cells which may ingest a great number of spermatozoa and this phenomeon may stimulate an azoospermy by failure of spermatogenesis. The study of human sperm (or testicular biopsies) by electron microscopy is needed to obtain the necessary information in order to orient diagnosis, prognosis and therapy.

[Ultrastructural characteristics of human spermatozoa with elongated head (author's transl)]. / Particularités ultrastructurales des spermatozoïdes humains à tête allongée.

In most spermatozoa with elongated head persists an abundant complex membranous system between the post-acromial zone and the post-nuclear region. This system has a periodical structure, the apparently spherical unit of which is 120 A in diameter; it develops between the two sheaths of the nuclear envelope and seems to be continuous with the innermost one. This system can be seen in spermatids during normal spermiogenesis and in most cases it seems to be eliminated either with cytoplasmic droplet or by swelling into the nucleus. Now, a comparable but permanent structure is located all around the head of the normal spermatozoon at the height of the posterior part of the post-acrosomial sheath. This latter system is organized under plasma membrane and only visible on the ultrathin sections made with an appropriate incidence. For some authors it might contribute to maintain the integrity of the head and that of the neck of the spermatozoon and so it might be comparable to a system of septal desmosomes. For other authors periodic structures might favour adherence and fusion of spermatozoon with ovocyte during fertilisation. The particular membranous system that we describe persists often in the spermatozoon with elongated head, by its exuberance it can trouble or delay the fusion of the two gametes at the moment of fertilisation, which might explain the sterility of men bearing this anomaly.

Ultrastructural study of arterial wall repair after argon laser micro-anastomosis.

A carotid end-to-end anastomosis was performed in 50 Wistar rats by means of a Coherent 900 argon laser. The vessel sealing was obtained with laser shots (average 19) of 300 mW power and 5-second duration, the beam being focused in a spot of 150 micron diameter (1,700 W/cm2). From day 0 to day 120, 25 specimens underwent semithin and electron microscopic examinations. The results showed the immediate sealing effect of the argon laser owing to protein denaturation and collagen fusion of the media and adventitia 100 micron in width. Re-endothelialization of the anastomotic line began by day 3, while myofibroblast proliferation was observed in the media by day 10. By day 20 media scar was still occupied by numerous myofibroblasts and surrounded by abundant collagen and elastic fibres. At long term the endothelial repair was complete and the anastomotic strength was assured by medial collagenous network.

Liver development in rats during the embryonic period (Carnegie stages 11-14).

The hepatic structures appearing during Carnegie stages 11-14 were analyzed in a series of 61 OFA rat embryos. The group of embryos (crown-rump length 2-7 mm, 10th-12th days after coitus) was composed of 52 specimens of the somite period (stages 11 and 12) and of 9 specimens of the postsomite period (stages 13 and 14). The embryos were submitted to serial histological sectioning with graphic reconstruction. Stage 11 was characterized by the development of the hepatic diverticulum induced by differential growth of the endodermal plate and fixed contact between the entoderm and endothelium lining the heart. Stage 12 presented obvious signs of cellular differentiation, the septum transversum giving the liver stroma and the hepatic diverticulum the epithelial trabecula. At stage 13 the epithelial cords enmeshed the stromal capillaries, while hepatocardiac veins drained the hepatic flow into the sinus venosus. Stage 14 was recognized by the presence and development of the hepatic lobes and the enlargement of vascular channels. The cystic bud was never observed. The identification of these features permits to precise the hepatic developmental staging in rats and to obtain accurate criteria for the characterization of the end of the somite period and the beginning of the postsomite period.

Mechanism of aneurysm formation after 830-nm diode-laser-assisted microarterial anastomosis.

OBJECTIVE: The process of aneurysm formation after laser welding is described. SUMMARY BACKGROUND DATA: The mechanism of aneurysm formation after laser-assisted microarterial anastomosis is presently unclear. METHODS: A series of 830-nm diode-laser-assisted longitudinal aortorrhophy with a condition of 400 to 500 J/mm2 for 1 cm length of anastomosis versus conventional manual anastomoses were performed in 90 Wistar rats. To compare this technique with normal media process, a histologic examination of aneurysm formation was conducted. RESULTS AND CONCLUSIONS: The results show that there are two important factors that cause aneurysm formation after laser-assisted anastomosis: 1) the vessel wall is damaged by laser heating; 2) proliferation of collagen fiber at the adventitia is absent during media reconstruction.

Liver development in the rat during the embryonic period (Carnegie stages 15-23).

Hepatic and biliary structures appearing during embryonic Carnegie stages 15-23 were analyzed in OFA rat embryos. The group of rats with crown rump length 7.5-16 mm and 12.8-16 days after coitus yielded 55 specimens (23 of stages 15-16, 20 of stages 17-18, 9 of stages 19-22 and 3 of stage 23). The embryos were submitted to serial histological sections with graphic reconstructions. From stage 15 to the end of the embryonic period, the hepatic gland and its vascular channels (transverse portal sinus and hepatocardiac veins) presented considerable enlargement while hematopoietic function appeared. At stage 17, occlusion due to epithelial proliferation was evident in the hepatic duct. At stage 18, the duct became recanalized and assured the continuity between liver cells and gut. From stage 18 to 23, biliary ductules developed in periportal connective tissue forming ductal plates which received biliary caniculi. Except for the gall-bladder which is never present in the rat, similarity and presence of the same hepatic structures in man and in the rat during the embryonic period stages 15-23 suggest that the rat is a good experimental model for liver development and will be useful in the understanding of congenital anomalies.

Quantitative changes in collagen levels following 830-nm diode laser welding.

BACKGROUND AND OBJECTIVE: The actual mechanism by which laser irradiation welds tissue is presently unknown; however, collagen is a major constituent of tissue welded by laser irradiation. STUDY DESIGN/MATERIALS AND METHODS: Collagen was extracted from the abdominal aorta of Wistar rats by acetic acid extraction and repeated pepsin digestion after tissue welding (254 W/cm2) by using an 830-nm diode laser. The collagen levels were determined by using the Sircol Collagen Assay (Biocolor, Northern Ireland). RESULTS: Compared with untreated aorta, the collagen content of the treated vessel was obvious decreased (P < 0.001) immediately after laser irradiation. Levels then increased by day 3, with a peak at day 10 (P < 0.002). The collagen content returned to normal levels on day 30 and remained at this level throughout the rest of the experimental period. CONCLUSION: These results suggest that a proportion of the collagen molecules in the vessel are denatured by the heat of the laser. Collagen synthesis is stimulated during the healing process after laser welding with the parameters used in the present study.

Morphologic changes in collagen fibers after 830 nm diode laser welding.

BACKGROUND AND OBJECTIVE: The mechanism of laser tissue welding is elusive, but collagen transitions are somehow involved. Collagen fiber modifications observed after 830 nm diode laser welding are presented in this study. STUDY DESIGN/MATERIALS AND METHODS: A 830 nm diode laser assisted longitudinal aortorrhaphy was performed on 37 Wistar rats, with shots of 0.5 W in power, 8 sec in duration and 250 W/cm2 in irradiance. Energy utilized ranged from 400-550 J/ mm2 for 1 cm-length of anastomosis. After laser welding, histological modifications in collagen fibers were observed through optic, scanning electron, and electron microscopic examination. RESULTS: After laser welding, collagen fibers lost a proportion of birefringence. Under electron microscope, the different changes in collagen fibers were visualized being either fused, "roped," swollen, or dissolved, surrounded by normal ones situated in the same zone. CONCLUSION: These data suggest that diode laser heating denatured part of the collagenic fibers, and that these morphologic changes play an important role in laser welding.

Biliary structures lead to tumour recurrences after laser-induced interstitial thermotherapy.

BACKGROUND AND OBJECTIVE: Thermal diffusion during laser-induced interstitial thermotherapy (LITT) has not yet been fully investigated in heterogeneous tissue architecture such as liver. LITT was performed on rabbit liver tumours to analyse the role of biliary structures in thermal diffusion. STUDY DESIGN/MATERIALS AND METHODS: Twenty-four VX2 tumours were grafted onto 12 rabbit livers. The animals were randomly separated into two groups when tumour size reached 8 mm. Thermotherapy was performed by delivering the 830-nm output of a diode laser to the centre of the tumour with a 300-,microm fibre. Irradiation conditions were 1.5 W over 900 sec. On day 7 or 14, the tumours were removed and stained with haematoxylin-eosin and picrosirius red F3BA (PR). Thermal damage was evaluated by PR and electron microscopic examinations. RESULTS: Among the treated tumours, recurrences were found both at the periphery (one on day 7, seven on day 14) and within the treated area (two on day 7, two on day 14). All recurrences were located in the vicinity of the biliary structures, which are frequently spared from thermal injury. CONCLUSION: Biliary ducts lead to a heat sink, thereby facilitating tumour recurrences.

Scanning electron microscopy of microarterial anastomoses with a diode laser: comparison with conventional manual suture.

A diode-laser (830 nm)-assisted carotid artery end-to-end microanastomosis (LAMA) and a contralateral manual suture anastomosis (CMA) were performed in 70 Wistar rats. The vessel sealing was performed on the left carotid by laser pulses (average 3) of 500 mW power and 4.5 sec exposure time, the beam being focused on a spot of 300 microns diameter (700 W/cm2). The CMA was achieved on the right carotid by six 10-0 stitches. From day 0 to day 210, 40 specimens underwent scanning electron microscopy. The laser impact produced a wall injury of 100 microns in width, with an immediate sealing effect due to protein denaturation and collagen fusion of media and adventitia. The anastomosis became re-endothelialized by day 3, while the longitudinal arrangement of the endothelial cells was restored from day 10 on. In the long term, a thick collagenous meshwork of collagen and elastic fibers maintained the strength of the media, while normal endothelium covered the anastomosis. Inversely, after CMA vessel repair was delayed, and the anastomotic line was more irregular and underlined by medial fibrotic scar. In both anastomoses, the patency rate was 93 percent, with nonlethal complications. The advantages of LAMA vs. CMA were: shorter operating time (13 min/22 min), reduced intraoperative trauma, better healing of endothelium, and a miniaturization of the laser source well adapted to microsurgery.